The Pro's Guide to Custom Cards: Create Balanced & Well-Respected Nonsense!

Lets not kid ourselves, there is something addicting in making your own cards, testing them, getting pissed off at the opponent playing “Pot of Greed” and imagining strangling them in their sleep. More often than not though, our own custom cards are… “Lacking”. This guide is all the experience I have accumulated over the years, for how to create a balanced game.

Step -1) Basic Required Skills

Creating cards is easy if you can check out most of the following, but if there is one thing you will learn in your journey through the custom card database, it’s that most people don’t:

• Basic Grammar: There are few things more disheartening on the internet that seeing a “your” used when a “you’re” should have been used, and likewise, it’s never a good sign if you see basic grammar mistakes on a card. It shows that the person who made the card did not care about what they were creating, or ~in the worst cases~ that they do not actually speak the same language as you. If you feel like you can’t communicate with your opponent, then it is highly unlikely that you will be able to play a game with them. You do not have to chat with them, but you should at the very least understand some common rules.   
• Knowledge of PSCT: If you’re not sure about the text format, just copy it from recent official cards, it’s that easy. Yugi is a game where a “;” and a “:” can change the outcome of the entire duel, you need to know how these work and in what order you should write the sentences so that they actually make sense (or, alternatively, so that reading them is easier).
• Basic Math: That’s not exclusive to Customs. A calculator in Yugi should serve as a score reminder and a log detailing how your score changed over time, NOT as a basic tool for doing math. “2400 – 1800” is a calculation whose solution you should be able to immediately find in your MIND, NOT ON YOUR SCREEN. Especially when I have opponents asking me questions like “how much damage” etc. it makes me lose faith in humanity. Yugi requires merely additions and subtractions people, those are basic life skills, not advanced mathematics, you NEED to be able to do those instantly. (and that’s coming from someone who failed Maths course for years in a row)
• General knowledge of the existing, TCG and OCG card data pool: There are two reasons for this: 1)Understanding the power level of the various tiers so you can adjust the power of your cards accordingly. 2)You need to know what already exists before you can create something original.
• Patience and time to waste: One of the most amazing arguments I heard recently in response to my criticism of a player’s custom cards, is that he had spent “a whole hour making them“. Just to be clear: That’s not how card making works. You will be playtesting those cards for at least 2-3 weeks after making them, starting from solo mode, then moving to proper matches once you have determined they are at the very least presentable, so you can work out their kinks and ideal balance. An hour does not begin to cover it, don’t be lazy.
• Creativity: Now here’s the trickiest of them all: Originality. A game I often play when people send me their custom cards to give opinions on, is to try and guess exactly which card they copy-pasted to make each archetypal card. It’s not a good sign when I can figure them out immediately. Wanna test this yourself? Easy: Take one of the most recent archetypes, for example "Adamancipators". See that the common effect of their tuners involves excavating the top 5 cards of your deck. Now go to “Deck Constructor“, go to the “Desc” box at the top right corner of the screen, and simply type in it “excavate the top 5” and finally click the option to show all Custom Cards. Count how many entire archetypes will pop up with that exact same mechanic (again: ARCHETYPES, not single cards, lets not be too optimistic) out of those 20+ pages of custom cards. Take your time, I’ll wait.
• Maturity: Like creativity, maturity is something I cannot give you advice on. The good news is, that unlike creativity which is more of a talent than a skill you can acquire, maturity is something that can be achieved over time. In custom cards, that translates to two things: 1)Accepting that you can lose. I’m not telling you not to make something practical, I’m telling you that the cards you make need to be beatable. (On that note, to the person who just thought “Well, my cards can be negated.”: Slap yourself. Hard. You deserve it.) 2)Accepting that there will be idiots, loads of idiots. There is no point in arguing with them, simply quit the duel on the spot, let them think about what they did wrong. If your opponent plays “Pot of Greed” or something similarly unreasonable, there is no takeaway from the duel, it simply doesn’t count, DON’T start powering up your Deck in the hopes that you will be beating “that” idiot, that’s how you will become an idiot yourself.

Step 0) Thought Process

While there is no specific order when it comes to thought process, having a generic idea on what we want the deck to do is important. The following order is not absolute, but it is the one I use:

1. Thinking of an image theme, (for example succubi, aliens, sewer monsters, etc etc), and gathering as many google images that you could potentially use as possible.
2. Thinking of the main mechanic of the archetype, partially based on the images you gathered.
3. Thinking of a name that fits said image themes and central gameplay mechanics.

Again, this is no absolute order. It's just what I've found to be the most practical, with my dysfunctional brain as a basis. Something else might work for you.

The thing is, if you want your deck to look good lorewise, then the images will often have to come first, then followed by thinking of the mechanics that would fit with said images.

Step 1) Name/Theme

Dos:

• Search for themes that have not been used until now. There are countless left, despite what you may believe. Your imagination (and google’s image results) is the limit.
• An easy way to do that, which I sometimes use, is making archetypes themed around specific old cards that no longer see play, because of how much they have been powercreeped over time, like Sparks/Mooyan Curry or Block Attack. Konami uses this method often as well, though they make the support around archetypes, not specific cards. Still, it’s an easy way to both think of a theme and create a balanced deck, since it all revolves around a generally weak card.
• Imagine you’re Konami, not yourself. What “would” you consider worthy enough of printing? Certainly not themes directly ripped from another franchise.
• Make puns. Buckets of them. The more puns the better. There can never be enough puns.
• Keep your themes “grounded”. Not every deck can have the “Almighty Creator Something Something” who nukes the field and has his own win condition.
• Your themes can have sub-themes. Personally for example, I make most female monsters Tuners.
• Depending on your Deck’s theme, recycling or even searching specific weak cards for free can be Ok, giving those cards a reason to be ran. Do this only for weak cards though. Having a "Harpie's Feather Duster" be more searchable/retrievable would just be dumb.

Don’ts:

• Fan decks. It's a bloody horrible idea and they NEVER turn out well. It doesn't matter how much you like Dragonball or Undertale or whatever other sh!t you watched/played last, it is NOT card material. Your cards cannot be taken seriously when you're fanboying.
• And being more specific about this: Don’t use f@cking Vanguard art. If you like it so much, go play Vanguard instead. I do.
• Continuing from the above: “Meme” decks, “Troll” decks etc, are all a big “No nos”. They're neither funny nor clever, they just make us think even less of you. Don't.
• Words like “Death”, “Hell”, etc. only sound good in your head. They come off as edgy, not to mention using them as archetype names starts creating all sorts of problems with already released cards. Be creative with your names.
• Divine Attributes and Divine-Beast type monsters. No… No. No.

An one-for-one searcher that does not generate card advantage and is not part of the archetype it searches, does not need opt restrictions. In fact fewer things in Yugi need hard OPT than you think.

Step 2) Images

Dos:

• 2D images, generally.
• Devianart is your friend.
• Sketches/Drawings etc.
• Anime waifus. Never enough of them.
• D&D guide art is often a good choice.
• Keep the art consistent. Yugi uses various artstyles for each archetype, but the artstyles within the same archetype are usually consistent. Just as how it would look bad seeing "Duston" art in "Burning Abyss", you should keep your cards with epic art from your cards with anime art separate.
• Many artists put a lot of effort into creating their images. Make sure you make that mute by removing the signatures (usually on the edges of the image you got off google). Microsoft Paint should be sufficient. Having tiny unreadable letters on your image tends to be a sign of low quality.
• For God’s shake, HAVE images in your cards, even if they are placeholders until you can find your ideal image. Facing a bunch of cards with a black square in their middle is NEVER fun. Cards need to be identifiable.
• Fanservice is always welcome, vulgarity isn't. Seeing some anime chick with a short skirt is eye candy, seeing some pornstar's tits randomly is just cringe. (not to mention you didn't pick a good one)

Don’ts:

• Images of 3D models. Sometimes it can’t be helped, but in general, they don’t look good. Stick to 2D.
• Real life photos. We mentioned above that noone is interested in seeing a meme deck. This extends to here. Avoid these like the plague. They look awful.
• Everything that is “too” low effort. I laugh at the Cyanide & Happiness shorts too, but they are not deck image material.
• Vanguard/MTG art. If you like those games so much, go play those games instead. Hell, I do, when I have had enough of "Mystic Mine" in rated 10 duels in a row.
• Using images of already existing cards. Poor “Meklords” are often the victims of this. There are always better, unused images out there for you to plagiarize, don’t piss on already existing cards, especially since it often ends up confusing when a card that looks exactly the same as a card you know from the irl game does something completely different (or even slightly different). Your own cards should LOOK like your own cards, not some other deck.

How to do proper image hunting, which you generally want to do en-masse (have a subfolder in your “Images” folder called “for cards” or something). Afterwards, remember to crop out any signatures, artist names, site names etc the images might have on them. Proper credits can have their time when you are sharing your cards on reddit, until then noone wants to see the image of your card stained with tiny unreadable letters. Microsoft Paint should be sufficient for the job.

Christen57 Guide to Image Cropping/Editing

(most of the linked articles you'll see here that aren't mine originate from him)

Step 3) Effects

This one is gonna be huge, so we might as well bring up the basics first.

USE PROBLEM SOLVING CARD TEXT (or PSCT for short). I cannot possibly stress this enough. Noone wants to read entire paragraphs without proper formats/terminology. In general, text seen in modern irl cards, is the basic guideline for how you should be writing your own. A few tips about that:

1. “Deck” specifically means the Main Deck. If it were to mean the Extra Deck, it would say so.
2. Everything left of “;” is a COST. Costs happen regardless of the effect being negated or whatnot, and they’re not part of the resolution chain, but happen the moment you activate the card. (PS: Technically targeting isn’t a cost, but for all intents and purposes you may treat it as such.)
3. Everything left of “:” is the condition for an activated effect.
4. If neither “;” nor “:” are on an effect, then it’s probably not an activated effect (for example: “Cyber Dragon“).
5. If you use numbers, it doesn’t target unless it says so. “Destroy 1 face-up card on the field.” means when the effect resolves, you will choose at that specific time, without a need to warn the opponent beforehand, what to destroy.
6. If you’re torn between using “when” or “if” for proper card texting, use “if”.
7. Permanent effects (for example: “Warrior monsters you control gain 300 ATK.“) are obviously only active while said card is face-up on the field, even if it is a monster. The card will state so if its effects work in the GY as well.
8. Numbers are written with their numerical symbols, and not as full words. You will write “5”, not “five”.
9. “Life Points” are now “LP“.
10. “Graveyard” is now “GY”.
11. “1 or more”, usually in the summoning requirements for Synchros, XYZ etc, is now written as “+1”.
12. “face-down Spell/Trap Cards” are now “Set Spells/Traps”.

You can find the full instructions for PSCT here.

Always count how many times your deck can do certain things, besides its main mechanic, after finishing it. The fact that individual cards are balanced, doesn’t mean the deck as a whole is.

The phrase "I drew godly/super good/amazing" etc. is a surefire sign that the player realizes their design is shit and is trying to cover for it to avoid the guilt. I've seen that pattern too many times.

ACTIVATED AND NON-ACTIVATED EFFECTS

To be clear, "triggered" is not an official term, but it is one widely used, so lets roll with it. To understand when an effect is considered activated, just look for 1 of the following 2 symbols: : ;

• : Everything left of ":" is a condition. The most common example is "Once per turn: Do X". If the conditions are not met, you cannot attempt to activate that effect.
• (A triggered effect is one whose condition is not something that can happen as a Spell Speed 1. For example: "If this card is Special Summoned: Draw 1 card." Triggered effects are Quick Effects, even if they do not say so, like the Yo-kai    girls.)
• ; Everything left of ";" is a cost. The cost will happen as soon as the effect is declared, so even if the opponent somehow negates the effect, the cost still had to be paid. For example: "You can pay 500 LP; inflict 500 damage to your opponent."

If an effect does not use either of the above symbols, then it is NOT ACTIVATED, and therefore does not start a Chain.

An example of a non-activated effect would be "Face-up Warrior monsters gain 300 ATK/DEF.", or "This card cannot be targeted or destroyed by your opponent's card effects."

What you want to keep as a creator, is that the more complicated the conditions are, or the higher the cost is, the more powerful the effects can become. Investment should be directly proportional to the output.

HOPT is just another nerf, it's not a mandatory requirement. Learn where to use it and don't stick it where it isn't needed.

THE MANY, MANY WAYS TO SAY “ONCE PER TURN”

We will expand on this later on, but with nearly 2 decades worth of cards, anything you make could be abused. This is the reason nearly all effects nowadays have some kind of limitation that only lets you use them one time per turn. Now, which cards actually “need” a limitation (surprisingly, it’s not everything) is debatable, but before that, lets give you the proper tools for limiting them. In the following examples, “X” will be the name of your card:

1. “Once per turn:”: One of the first and most basic types of limitation. This means that while that specific card is face-up on the field, you can only use that effect once per turn. An example of this is “Abare Ushioni“. So, if you normal summon “Abare Ushioni”, you get to activate its effect once per turn. This basic “Once per turn” limitation though only refers to that specific card that is currently face-up on the field. So, if you summon a second “Abare Ushioni”, you can use the second one’s effect properly. Alternatively, if you remove the first “Abare Ushioni” from the field (for example with “Dark Hole“) and then bring it back (for example with “Monster Reborn“), then you can use his effect again. Nowadays “Once per turn” is mostly used for limiting continuous spells/traps that are not searchable, or do not do anything mind-blowing. Keep in mind that it is completely pointless to use this wording on cards that will not stay on the field, for example normal Spells/Traps or effects of discarded monsters.
2. “You can only activate 1 X per turn.”: Mostly used for spells/traps, this texting means that you can only activate 1 copy of the card per turn. So, even if you have 2 “Zefra Providence” in your hand (or face-down on the field), only one can be activated per turn. This is surprisingly less limiting than you would think, as activating a card and activating ITS EFFECTS are 2 completely different things. When banishing a card from the GY to use its effect, for example the aforementioned “Zefra Providence”, you are NOT activating the card itself, but its effects instead (in the case of “Zefra Providence” not even an effect is activated but that’s another can of worms). In other words, if you have 2 “Zefra Providence” in your hand you can only use 1 of them to add per turn, but if you have 2 of them in the GY, you can use both of them on the same turn to protect your “Zefra” cards. Obviously if you add a card with “Zefra Providence”, then on the same turn your opponent would destroy a “Zefra” card you control with a card effect (“Mystical Space Typhoon” for example), you can use the same “Zefra Providence” you played this turn to protect your card. In another example, a card like “Hidden City” only prevents you from playing another copy of it with this limitation (basically to block you from adding). Once “Hidden City” is face-up on your field, you can use all 3 of its effects (if possible) on the same turn.
3. “You can only use this effect of "X" once per turn”: This limitation is always written right below the effect mentioned. “Dark Contract with the Gate” has this limitation, meaning you can only activate this effect to add once per turn, but you can add as many copies of “Dark Contract with the Gate” as you want per turn, so long as you only use the adding effect once. This limitation only works for ACTIVATED effects, and as we mentioned earlier, “:” and “;” are used to signify activated effects. Therefore, if you play “Archfiend Palabyrinth“, activate its effect to summon an “Archfiend” from the Deck and then activate another “Archfiend Palabyrinth”, replacing the first one, the 500 ATK bonus WORKS NORMALLY. This kind of limitation, along with the one below (which is basically an extension of this), is the most commonly used limitation today, as it is absolute. Regardless of where the card goes or how many copies you have,  you can only use the effect of X once per turn. There are very few ways to cheat this system, and that is usually by having a different card copy the effects of the card with the limitation. Spellbooks do this with “Spellbook of the Master“, as the limitation is placed on the NAME of the card, not the effect itself.
4. “You can only use each effect of X once per turn”: Basically an extension of the above limitation, but placed on all the ACTIVATED effects of the card. “Altergeist Multifaker” is one of the most infamous examples of this, as you can use her first effect to special summon her from the hand, then immediately trigger her second effect because she was special summoned, even if it was by her own effect. You will be using #3 and this the most.
5. “You can only use 1 effect of X per turn, and only once that turn.”: This means the card has 2 (or more) effects you could possibly use, and you are only allowed to use 1 of them per turn. The whole “Burning Abyss” archetype works with this, forcing you to choose between free special summoning them from the hand OR their GY effect. Due to the second half of the limitation, you can only use the chosen effect once as well. In the case of the linked “Graff” for example, if you special summon him from your hand with his effect, you cannot use his effect to summon something from the deck later, when “Dante” detaches him.
6. “You can only use 1 effect of X per turn”: A twist of mine to the above limitation, this lets you use 1 of the card’s effects per turn, but as many times as you want. Obviously you should be careful when using this kind of effect, as with any effect that does not limit itself to once per turn. That’s where the conditions (reminder: everything left of “:”) and the costs (reminder: everything left of “;”) come into play.
7. "Once per turn: You can activate 1 of the following effects. You can only use each effect of "X" once per turn: A farther twist! This goes exclusively for cards that will stay on the field, like continuous spells etc, that have multiple effects. With this text, different copies of said cards will not be useless, as they will be able to trigger different effects of the card.
8. “effect” + “You cannot do the kind of effect you just did for the rest of the turn.”: This is a much harsher restriction than the ones we have seen until now, as it completely locks you from doing certain actions for the rest of the turn, not just playing a specific card. “Pendulum Halt” is an example of this. After activating this (and going to a sweet +1), you cannot activate ANY card that would make you add cards from your deck to your hand for the rest of the turn. So after playing “Pendulum Halt” the “Upstart Goblin” in your hand is useless for the rest of the turn.
9. “You can only use this effect/activate the effect of X once per duel.“: Used to limit things that are usually way too convenient for their own good. “Spore” and “Glow-up Bulb”  got this treatment, as they were cards that could be played from the GY with no real cost, giving a player free materials for more summons. As you can imagine, this is the ultimate form of limitation for a single card. You simply can’t do that effect again in the same game. (edit: I believe that with the new rules, if that effect is negated, you can attempt to use it again).

Since my “Succubus” deck has a love for “Block Attack”, many of its cards are centered around punishing the use of Links.

A small guide Christen57 made for proper capitalizing on your cards:
https://docs.google.com/document/d/13lyi0MB06-fFY3KFbnhTmcC7weq4tHLOULrmNBg_Lh8/edit

THE GOLDEN RULES FOR SINGLE CARDS

First, an easy one, and one that Konami themselves have been enforcing since 5Ds: 

• Cards should never be a direct upgrade or exact copies of already existing cards (excluding cards from the very early game). Deck A can be better than Deck B as a total, but card A should NOT be better than card B in every possibly situation. 1) If “Monster Reborn” exists, then there should NOT be a generic Normal Spell with the text “Target 1 monsters in the GYs; Special Summon it, then inflict 500 damage to your opponent.“, as that would be a direct upgrade of it. 2) If “Mystical Space Typhoon” already exists, then you should not make a Quick-Play Spell that only says “Target 1 Spell/Trap on the field; destroy that target.“, even if it is part of an archetype. 
• Taking “Mystical Space Typhoon” as an example again, you will see that for all the spell/trap removal they have introduced after it (“Galaxy Cyclone“, “Cosmic Cyclone“, “Twin Twisters“, “Double Cyclone“, “Dust Tornado“, “Paleozoic Olenoides“), none of it is a strictly better card than good old MST, they all have their uses.

• The more generic a card is, the more careful you have to be with its power. And vice-versa. A “Laval” exclusive Spell that says “If you control a “Laval” Synchro Monster: Destroy all monsters your opponent controls. If a FIRE Synchro monster you control would be destroyed by battle, you can banish this card from your GY instead.” is fine, despite being an unrestricted version of “Raigeki“ with spice on top, because it requires its archetype to function, so being searchable/recoverable isn’t as much of a problem.
• Think of generic cards as the “general armor” that all classes in an RPG can equip, while each class also specializes in its own kind of armor, that being the archetypes. For example “heavy armor” for warriors, “light armor” for thieves, etc. Since general armor is accessible by all classes, it would be really hard to balance the game if said “general armor” was on equal terms with the class specific armors, that have REQUIREMENTS to be worn.

• Cards are in the banlist for a reason. You are not smart if you make banned cards as customs to rig the system, you’re a retard. Stop it.

• “The meta is worse.” is not an excuse for making intentionally unbalanced cards. Ignoring that the actual meta is rarely as unbalanced as people think if you actually read the cards, this argument simply proves ignorance.

• Don’t make anything you wouldn’t want to face. Always imagine your opponent playing the card you just created. How fair does it seem?

• Floodgates work for BOTH players. In other words, if a Spell/Trap unconditionally disallows an action continuously, it should not affect just the opponent. An easy search in cards’ descriptions will reveal that konami has not released a single continuous spell/trap or field spell that specifically blocks the opponent from doing actions unrelated to your own cards, EVER. That’s 20+ years of yugioh history, for a reason.  You should always be ready to be served your own poison. Even the most infamous lockdown continuous cards in yugi, like “Vanity’s Emptiness“, “Mistake” or “Imperial Order” always affect BOTH players.
• Now, you might build your deck around not having to use said locked mechanics, but simply creating a continuous spell for example that states “Your opponent cannot draw cards.” while you play “Upstart Goblin” would be both infuriating and unfair. 
• Monsters with lockdown effects only for the opponent are generally more ok, like “Thunder Dragon Colossus“, because monsters are always considered more vulnerable than Spells/Traps.

• Nothing, ever, activates itself from the deck. Grow up. If you banish a card from the Maindeck or Extradeck at the start of the duel with its own effect, you have a valid reason to delete your account and wear a “dunce” hat, you utter moron.

• No card should unconditionally generate card advantage. “Card of Demise” has proven itself to be the epitome of bad design, despite the gazillion restrictions placed on it. No searcher should ever get to add 2+ cards at the same time, without having a very big downside to it or extremely strict conditions for using its effect. If a card increases the total number of cards you have in your hand & field, then you should be very stingy with whatever other effects it may have and place further restrictions on what you can play for the rest of the turn.

• Effects should never be able to lower the opponent’s hand balance on the first turn. There are no excuses for this. It is the reason “Deliquent Duo” is banned and is never coming out of the banlist, and “Apoqliphort Towers” was once in the banlist. You can go nuts with destroying cards your opponent controls, and you can use as many effects as you want for replacing harmful cards in the opponent’s hand (“Dragged Down Into the Grave“), but it is NEVER acceptable to lower the number of cards in the opponent’s hand without requiring actual interaction with the opponent.

Reminder that the more specific the crime, the harsher the punishment can be. Also reminder that Traps are allowed to be much stronger than Spells, or handtraps (monsters) respectively.

• Make positive triggered effects mandatory if possible. This is a suggestion, not a rule. For example if your monster says “If this card destroys a monster by battle: You can Special Summon 1 monster of X archetype from your Deck.“, make it “If this card destroys a monster by battle: Special Summon 1 monster of X archetype from your Deck.“. Virtually nothing changes for your strategies, but it lets smart opponents take advantage of it. I believe it promotes smarter gameplay.
• Not everything needs to be an archetypal card. I often get in the mood to just make singles, so I can empty my “card images” folder a bit off images I have collected from Google because I thought they would look nice on cards. Naturally generic cards need to be a bit weaker than archetypal counterparts, but on the other hand you can pretty much run them on anything. Take my “Queen of Arrogance” as an example.
• Gambling takes balls. Go through Konami’s list of luck-based cards, and you will see that literally ALL of them have the potential to blow-up in your face, or otherwise fizzle. One of the most infuriating arguments I have heard is that “luck-based effects need to be all positive to be viable”. Don’t. Do. That. That’s. Cowardly. Approximately 50% of your luck-based effect’s possible results should be negative ones, or otherwise self-negating (that could be all Tails effects for coins for example, like the “Arcana Force” did.). If you're not gonna gamble, just give your cards the actual effects with no coin/dice involved and be done with it.
• Paying 500 LP is not a real cost. Obviously I'm talking about some of the more absurd effects one can see out there that only need to happen once, for example the typical "Pay 500 LP; Special Summon 2 "X" monsters from your Deck."

Neither of these effects is hopt, but more importantly: They don't need to be.   

• Give very specific protections, if you have to. “Unaffected by other cards’ effects.” is way too powerful a protection that NO SPELL/TRAP HAS EVER HAD. Even amongst the monsters, it is very rare to see this kind of protection given permanently and unconditionally. It is also very rare for a boss monster to have battle protection. You can combine cards to give all sorts of protections to your cards, but having a card have full blown protections from both battle  and from effects on its own is just idiotic. A card can give other cards protections, but protecting itself fully is just nonsense.
• Activations and Summons very rarely, if ever, have negation protection for themselves. In this, include preventing the opponent from responding.
• Keep your texts small! Use the PSCT rules to makes your card’s text as small as possible. NO ONE wants to read 2-3 paragraphs to understand just what one card does. As a general rule, if your card text requires scrolling down DB’s text box after hovering the mouse over it (aka after displaying the box to its maximum length) then you are probably doing something wrong.
• Cards have 2-3 effects on average. 1 of these will usually be your archetype’s main mechanic, another will be a summoning condition or an effect that activates upon summon/activation, and a third will be the unique effect of the card. Add or take a non-activated effect from this, and do not count the OPT restrictions. The main goal is for your cards to be easily readable. If your card has too many activated effects it is more likely that you will misplay it than the opponent, I've seen this time and time again.
• The word “until” in effects that involve changing card balance is a recipe for disaster. The most infamous examples of these are “Evenly Matched” and the damned “Card of Demise“, cards that have been horribly abused by all the wrong decks due to how awfully designed they are. Avoid that.
• Be very careful with what effects you give Link 1s. Links monsters are the only Extra Deck monster that can be made out of only 1 Maindeck card as a material. Consider whatever effect you give Link 1s to be an additional common mechanic of your archetype. If your opponent's Link 1s unconditionally increase their card balance, you have a valid reason to leave the duel.
• Links are kept in the Extra Deck, and are accessible at any time. If a Link 1 has the effect to add a card from your Deck to your hand without a cost, then that automatically turns Every. Single. Monster. of your Main Deck into a searcher, or otherwise a +1. Depending on what they add/Summon/do that may be fine, but you need to be careful about that kind of stuff. Also note Link 1s should also NOT be able to use Link 1s as materials for their own Summon. Related to that: DON’T MAKE LINK 1S THAT CAN SPECIAL MONSTERS FROM THE GY FOR FREE. It is debatable if that kind of effect should be given even for Link 2s, let alone Link 1s. (One of the stupidest patterns I have recognised, is people creating Link 1s through 3s that Special from the GY. The worst part is that these retards often consider themselves smart.)

Card balance determines everything. The higher the cost in card balance, the more powerful the effects can be.

Instructions on creating Pendulum Links by Christen57 (personally I wouldn't recommend making new card types like that, but it's a cool trick).

THE GOLDEN RULES FOR WHOLE ARCHETYPES

• Have only 1 unconditional type of search per card type (monster/spell/trap). An unconditional search includes: Activating a Spell card, summoning a monster with any method (don’t include normal summoning in this), just activating a monster effect with no requirements, a card discarding itself to add another.  Generally things that do not lower your total card balance and do not require any interaction with the opponent. Giving 2+ monsters the ability to search an archetypal card when they are just Summoned without that being the archetypal mechanic is broken. Likewise, having more than one card that can just be discarded and immediately search something else to take its place is purely broken, even moreso if it can search another searcher.
• Effects that search should be HOPTs. Exceptions to this rule include: A)If the searching card itself is not part of the archetype. B)Searches triggered off battle, or otherwise extremely demanding conditions.
• For god’s shake COUNT how many +es your deck has. A + is considered an increase of the total number of cards in your hand and field. “Pot of Greed” for example is a +1, because the total number of cards you have on the field/hand will have increased by 1 after resolution. Yugi is a game that uses cards as resources, so this indicates how many potential moves you have left. I am sick and tired of seeing archetypes where every single card generates card advantage. You’re not smart when all of your monsters give you an add or summon, you’re retarded.
• The main mechanic of the archetype should be clear. This is more of a suggestion than a rule, as some archetypes, usually the anime ones (say “Blackwings” or “Performapals“) do not have a central mechanic, but especially in customs, where it is almost guaranteed that the opponent is seeing your cards for the first time, it is imperative that it is clear how the deck works. This also helps your deck be more memorable. A helpful way to go about it is this: Make sure someone could pick any 2 maindeck monsters from your deck and immediately figure out what the deck’s mechanic is. This helps with the readability of the cards as well. A reader can immediately filter out the text that is common with the other cards of your archetype and go to the unique effect of the card. 
• If possible, all your monsters should have a common, archetypal mechanic, apart from their unique effects. If you can pull that off for the Spells/Traps as well, even better.
• Apart from the archetype’s mechanic, avoid repeating effects. Say for example your archetype’s main mechanic is swapping monsters you control for ones in your hand. Having 2 different monsters in the main deck (or 2 different monsters in the extra deck) where both of which have the effect to destroy a Spell/Trap when summoned would just be silly. Make the effects different somehow. For example one could destroy a face-up Spell/Trap while the other a face-down Spell/Trap, that sort of thing. Only the archetype’s main mechanic should be strictly copy-pasted among different cards in your deck.
• Be stingy with removal that doesn’t target or destroy. And vice versa, feel free to create protection specifically against cards that do not target and do not destroy. I affectionately call those kinds of defenses "protection from bullsh!t". My go-to text for this is usually "Unaffected by your opponent's activated card effects that do not target or destroy it." With this "Dark Hole" will work, "Mind Control" will work, but "Dingirsu", "Tiaramisu", "Zeus" etc. won't.
  
  
  
  

  

  Spells/Traps do NOT unconditionally protect themselves. One of the most downright stupid things I have seen is "once per turn, this card cannot be destroyed by card effects" on Spells/Traps. Don't do that sh!t. If a Spell/Trap protects itself, then it is done on a condition THAT THE CARD CANNOT ACHIEVE BY ITSELF. Just to be clear, the ONLY Spell/Trap in the game that has unconditional self-protection is "Seal of Orichalcos" which is ONLY a minor stat boost that also locks you out of your extra.

  
  
• Summoning straight from the Deck is not all that common. While Konami seems to be turning towards that direction lately, like generic counter traps, archetypes have at most 1 card that can Summon straight from the Deck. Do not overuse this type of summon.
• Don’t make archetypal support for IRL archetypes that don’t need it. You know what we’re talking about. “Lightsworns” don’t need more support. “Six Samurai” don’t need more support. “Frightfur” don’t need more support. “Elemental Heroes” definitely don’t need more f@cking support. An already busted deck having more ways to abuse its already broken cards is never fun or praiseworthy.
• Don't remake existing decks. An extremely disappointing pattern I have seen: Decks that are exact copies/upgrades of existing decks, just with different names. For some reason "Altergeist" are most often the victims of this. People who do this should probably kill themselves.
• See what the current meta is like. For all the bitching that people do about “Orcusts“, the deck only has: 1 Set from Deck, 1 Summon from Deck, 1 Summon from GY, 1 Mill, 1 Counter Trap and 1 potential draw card that noone runs. Same goes for “Salamangreats“: 1 Add from Deck (and only for monsters), 1 Mill, 2 Summons from GY and 1 Counter Trap. Both of these decks are considered top meta choices with only these few effects. Do you understand why your Deck should NOT have 5 different Summons from Deck?
• "Ritual Beasts" and "Dragunity" exist. The 2 go-to ideas of unimaginative people for custom archetypes are Summoning banished monsters and placing monsters in the Spell/Trap zones. I don't know why, and I don't care.

Personally I think effects that Special from the hand should never need opt on their own to begin with, and that especially goes for ones with no-monsters control requirements like this guy. As for the reason his order of effects is inverted from what it should be, see below.

THE GOOD COMMON MECHANIC

I will do a whole article in the future about good and bad common mechanics in the real game, but I believe it is important to at the very least mention it here: Your common mechanic needs to MATTER. Your deck needs to be recognizable by its playstyle, and it needs something strong to revolve around so you don't have to be cheap.

As an example, lets take "Madolche" and "Tenyi". "Madolches'" common mechanic is merely that they get reshuffled in the Deck when destroyed. That's a WEAK common mechanic, and exactly because it's weak, Konami has needed to give them a sh!tload of interchangable generic searchers to make them playable (they have five differnet Specials from the Deck ffs...). "Tenyi" on the other hand only have 2 searchers (and one of them is horrible, so practically 1), and neither of them has "Tenyi" in its name, meaning they are not  searchable, because their common mechanic, ~free-Specialling from hand and popping free GY effects~ is strong. 

What I'm getting at, is that if you have to choose between A: A lackluster common mechanic that you will have to balance out with a sh!tload of interchangable consistency-boosting cards, and B: A strong common mechanic with barely 1-2 consistency-boosters, always go for B. Make your archetype have an IDENTITY, not a gimmick.

Don't be stingy with how strong your common mechanics are.

No, really, which of these 2 will you remember existing a few months from now? Which of these 2 ACTUALLY MATTERED in the gameplay of their own Deck?

READABILITY

As stated above, about the average number of effects cards have and how the main mechanic of the deck should be clear, it is of paramount importance that your card is easily readable. As such, you should write your cards’ effects in a proper order, so a player can immediately see which effect you are using. In general, cards effects are written on cards in the most likely order they would activate. Since that can be more complicated in monsters, this is what we’ll present here.

So the order of possible effects for monsters is:

1. Materials for Summon (in the case of Extra Deck monsters). The typical “2+ Level 4 monsters” and the like.
2. The archetype inclusion in case the name does not directly cover that (“This card is always treated as a “X” card.“), for example “Edge Imp Frightfuloid“. Keep in mind, in normal monsters this is actually written after the flavor text, not before.
3. Effects activated by discarding/sending the card from the hand to the GY.
4. Alternative to #2, passive name change effects while on the field. (for example “Amazoness Princess“)
5. Conditions for Summon/ways of Summon from hand/Extra Deck. (“This card must first be Syncro Summoned.“)
6. Effects that activate upon Summon. (“If this card is Special Summoned: Target 1 Equip Spell in your GY; add that target to your hand.“)
7. Non-activated effects (passives) they have face-up on the field. This usually includes protection effects (“This card cannot be targeted by card effects.“), attack boosts, etc etc.
8. Activated effects they have face-up on the field (“Once per turn: You can target 1 face-up Spell/Trap on the field; destroy that target.”)
9. Effects they have when destroyed/sent from the field to the GY/when used as a materials. (“If this card is used as a material for the Fusion Summon of an “Elemental Hero” monster: Draw 1 card.“)
10. Non-activated effects they have in the GY. (This is not all that common in the IRL game. A good example would be “Phantom Beast Cross-Wing“.)
11. Ways to Summon them from the GY. (“You can Special Summon this card from your GY, but banish it when it leaves the field.“)
12. Activated effects they have in the GY. (“You can banish this card from your GY; “Blackwing” monsters you currently control gain 300 ATK until the End Phase.“)
13. Non-activated effects they have while banished.
14. Ways to Summon them while banished.
15. Activated effects they have while banished.

Notes:

• Name-related restrictions are placed immediately after you have listed every single effect they cover. Take for example my “Starfriend Blits” from above.
• There are no “official” rules about the order of card effects. Since the end-goal is just easier readability, you can make an exception and inlcude the archetypal mechanic part of the effect first or last, regardless of proper order, so the opponent can quickly skip over part of the effect he already knows and go to what makes the card unique. 
• As an example, in the case of my “The Endless” for example, I would normally include the restriction each monster has “You can only Summon “X” once per turn.” ) at the start of their text, since that restriction would likely come into play immediately after they are Normal Summoned from the hand. However, I opted to put it at the end of the text instead, along with the other archetypical mechanic (“If this card is destroyed and sent to the GY: Target 1 “The Endless” monster in your GY; Special Summon it.“), since both are common texts in all of “The Endless”, and I wouldn’t want the opponent to have to read “common text” -> “unique text” -> “common text”.
• Using bullet-points like the “Burning Abyss” did might help if the exact same activated effect repeats on every monster. Basically it makes it even more obvious which line can be skipped in order to get to the actual unique effect of the card.
• Again: BULLET points, not "1)...2)... etc", NOT "-do X -do Y". Use these: ●
  ONLY these. Personally I have bookmarked "Arcana Force IV" (my favourite "Arcana Force" monster) and just copy-paste them from there every time. https://yugioh.fandom.com/wiki/Arcana_Force_IV_-_The_Emperor

Equip Spells that DO NOT provide card advantage (so basically no "Premature Burials" or equivalents because then they are just searchers with extra steps) are perfectly fine being strong. See most modern Equip Spells as an example.

THE TOOLBOX

While there are exceptions, in general there are some specific, generic effects most of which you want your deck to pull off (preferrably with only 1 card achieving each of these). Quite often, Konami’s archetypal cards are basically a combination of the unique archetype mechanic + 1 of these, for each monster, since the monsters are usually the most searchable type of card in the deck, and the most easy to both use and be countered, making them more fair than spells/traps. It is an easy way to make cards, it covers most of your deck’s basic needs to counter the opponent, and it still leaves room for creativity.

• The searcher. Quite obvious, the archetypal searcher is almost always needed, in every deck. Usually the card you’ll be running X3. People will often leave this to a monster "If this card is Summoned: Add 1 "X" card from your Deck to your hand." Personally I'm not a fan of this method but to each his own. For example: Virtual World Mai-Hime - Lulu
• Monster destroyer. An effect that targets a monster on the field (or doesn’t target it but is more restrictive), and makes it go boom. Usually the card you end up running 1-of in your irl decks, but is still needed in case the opponent summons something weird. For example: Yoko, the Graceful Mayakashi
• Spell/Trap destroyer. Similar to the above, this is the generic backrow remover. You will usually be running this X2. Personally, I often make a distinction between face-up and face-down spells/traps, and have 2 different cards for those. For example: Tengu, the Winged Mayakashi
• The negate till turn end. Less destructive, equally protective, usually an X2. Targets a face-up card your opponent controls (usually not a quick-effect, since that would turn it to disruption) and negates it till the end of turn, without destroying it. Often unrelated to Special Summoning, so you can use it at any time to temporarily disable a floodgate. For example: Alich, Malebranche of the Burning Abyss
• The summon from GY. Quite often decks will leave this effect to spells/traps instead of monsters, but others will prefer giving that effect to monsters when they are Summoned. For example: Appliancer Reuse
• The tuner/fusioner/xyzer/linker/ritualer. Maindeck-focued archetypes will often have a monster that specifically focuses on getting the extra deck monsters out. For example: Zefraxi, Treasure of the Yang Zing
• The GY removal. Usually an once per turn effect (and not a quick one) that targets a card in the GYs and banishes it. Useful for disrupting annoying plays and almost mandatory in today’s game. For example: Mecha Phantom Beast Sabre Hawk
• The protector. His effect protects your other archetypal cards from specific kinds of removal. Usually an X1, that you want to be able to Summon quickly from the hand or GY with some kind of effect, so that you can use his passive protection as a disruption. For example: Aria, the Melodious Diva
• The miller. One I rarely use personally, this works similar to the searcher, sending a specific card directly from your Deck to the GY, and is usually a key play-enabler. For example: Armageddon Knight.
• The free material. This is one of my favourite tropes. Basically a monster whose sole purpose is being a +1, free Specialling itself from the GY, triggered when the archetype uses its common mechanic. A different category from the self-resurrecting boss that Structure Decks often utilize. For example: Superheavy Samurai Fist

Remember: The Opponent is probably seeing your cards for the first time. You can ignore proper effect order a bit if it makes your card more easily readable (for example you could stick all common mechanics right next to each other).

In my experience, whenever you see too many cards archetype-lock (ie "You cannot Summon monsters for the rest of the turn, except "X" monsters"), it's a sign of guilt. The creator usually knows they've f@cked up with the design and overdone it with the Deck Specials and the free GY revivals, and they're trying to hide it, from themselves as well as others, by adding restrictions that do not really restrict anything.

LAX RULES

We have been talking about what you should not do all this time, what you need to desperately avoid, and what you should “probably” avoid, but there are times when you can be a bit more lax with the effects you’re using.

• Field Spells: In general, Field Spells in  Yugioh are known to often be the single best card of most archetypes. It is mostly considered OK for a field spell to generate card advantage on its own, like adding 1 card of its archetype to your hand upon activation, apart from the rest of its effects. Since each player can only control 1 Field Spell at a time, there is less chance of them being abused, by running multiple copies, so you can be a bit more lax with them. It is also generally OK if the Field Spell adds the card that can also search it back, assuming at least one of them is a hard opt.
• Searchers that are not part of the archetype they support. A quite easy way to balance your own Deck, making sure your own searchers are not easily searchable/recyclable is a good way to keep your Deck fair. “Gem-Knights” use “Absorb Fusion” for this, “Crystal Beasts” use “Rainbow Bridge“, etc etc. When using such cards, you can even do away with the once per turn restrictions, despite them being unconditional searchers.
• When destroying monsters by battle or inflicting battle damage: Both forcing the opponent to discard and Summoning straight from the Deck are generally considered OK if the condition for them is first winning a battle against an opponent’s monsters. Same goes for searching.
• Adding cards from the GY/face-up from the Extra Deck to the hand. It is not rare for an archetypal or attribute/type specific recycling card to add more than 1 card from the ones you have already used back to your hand. Though it generates card advantage, it is far less problematic than fetching new cards from your Deck, while also giving the opponent a chance to respond, as cards in the GY are far more vulnerable than cards in the Deck. Good examples of this are “Salvage“, “Qlimate Change” or “Quick Charger“.
• What sub-types do. Sub-types are “Tuner”, “Toon”, “Gemini”, “Union”, and “Spirit”, the thing Duelingbook calls “Ability” in its card creation screen. Though there are some things that you are used to seeing on them (for example geminis requiring a second Normal Summon to get their effects), these are just parts of the effects of the already released cards, and not absolute rules included in the rulebook. Konami themselves have changed their mind 6-7 times about how Toon monsters actually work, and a few less times for Unions. As long as you keep the theme somewhat close to the original, it is ok to be creative with how to use these sub-types.
  
• When relying on overly weak&simplistic cards. Having free searches for such cards is generally not problematic, even if technically they are +1s. Konami has been doing that with "Umi" for a while.
• Extend this to simply including such cards in your deck without overly focusing on them. If a card thematically fits your deck (for example my “Timeless“, who are golems (earth rocks) use “Fissure” and “Earthquake“), and it is a weak TCG card, why not make it ~kinda~ part of the archetype? No need to focus on it with your entire deck, just make a specific member of the archetype able to search it in some way.

While "Dragoon" himself gets all the hate, people are not getting that he is NOT the source of the problem. He is a strong Fusion, yes, but not broken. What makes him problematic, is "Red-Eyes Fusion", that allows you to use the materials from the Deck. Going -2 while keeping bricks in your hand to Summon "Dragoon" is perfectly acceptable. Wasting zero resources to Summon him with only one card needed ("Red-Eyes Fusion"), that's when the sh!t starts. It is perfectly acceptable that investments of multiple card combinations can create powerful states/strong fields. Getting the same results from ONE card is when the game gets broken.

• When effects concern Normal Monsters. Normal monsters are much more straightforward and have far fewer surprises for the opponent to deal with, and as a result are generally more OK to mess around with. Cards like “Dark Factory of Mass Production“, “Unexpected Dai” and the gravely underestimated “Tri-Wight” are proof enough of this.
• When effects work in the End Phase. “Rokkets” Summon monsters straight from the Deck to replace themselves whenever they are destroyed. If this didn't happen exclusively with a delay (aka in the EP) then it would be problematic. Giving the opponent an entire turn to respond before you get a chance to use them as materials for Summoning something bigger and potentially more dangerous from your Extra Deck makes this mechanic fair.
• The more specifc the sin, the harsher the punishment can be. A counter trap that says “Negate your opponent’s card effect if you control an “X” Link Monster.” for example is not something that can afford to punish heavily, but a counter trap that says “If an opponent’s Normal Spell Card is activated that would Special Summon a monster from the Deck: Negate that effect and banish that card, then inflict 1000 damage to your opponent, also your opponent cannot Special Summon from the hand or Deck until the End Phase.” is actually acceptable since the condition for its activation is much stricter. Again and again: Investment should be directly proportional to output.
• Effects when used as Fusion/Ritual Materials. This also applies to a lesser extent for other kinds of materials, but even moreso for Fusion Materials, especially if there are no Contact Fusion shenanigans. Good old “Polymerization” Fusion makes you go -2 at the very least, so triggering a few free effects from that is not a problem, and for the most part should not even need opt restrictions.
• When triggered effects are mandatory. Depending on the effect you might even use this to get rid of opt limitations. “If this card is Special Summoned: Target 1 Spell/Trap on the field; destroy that target.” is an effect that will happen every time the monster is Special Summoned, even if the opponent has no backrow but you do. As we said above, it allows the opponent to play smart, making your strongest cards backfire with good plays.
• Effects triggering from Normal Summon. A Normal Summon is something that only happens once per turn by default, it's a sort of restriction on its own. It's fine if it gives you a bit of +ing on its own, like a Deck/GY Special or something.
• Special Summoning from the hand. A type of effect that I never considered to need opt limitations on its own. The number of cards you have remains the same, it just allows you to actually use the stuff you have.
• Traps. And we do not mean ones that activate from your hand. We mean normal, regular Traps. More details on that below, but basically Traps are slow, and Konami knows that. Provided they have some kind of activation condition, they can be strong, or self-recurring.
• Equip Spells. An Equip Spell does NOTHING on its own as a card, so you are allowed to go pretty nuts with what boosts they provide your monsters.
• Just to be clear, this does not include the likes of "Premature Burial", which are combo extenders with extra steps.

Bullet points can be your friends for making your card more readable. For example the second bullet in all my "Vurkos" is their common mechanic of reforming during the EP, so the opponent can immediately filter it out when reading the cards. And just to be clear: I mean BULLET points, those cute round black dots, not whatever you found more convenient at the moment.

HANDTRAPS VS. TRAPS

Unlike everyone and their mother, I find handtraps perfectly acceptable. They're not a "necessairy evil", they're perfectly valid cards (hell, for most of the existing ones I'd say they don't even need their hopts, like the Ghost Girls). Handtraps might be negates from the hand or maybe one-time battle boosts, but here is the thing: They are JUST that.

Regular traps on the other hand, the ones that need to have been Set for a whole turn before activating, are for that exact reason becoming more and more powerful over time. In the past 2 years we have gotten "Titanocider", "Ice Dragon's Prison", "Get Out!" and other crazy stuff that I have absolutely loved. If you were to compare the handtraps and regular traps without including the setup regular traps need, you'd see that handtraps are basically ultra-nerfed versions of regular traps.

What I'm getting us, is that if your card has a certain effort required to be used, you can go nuts with it, and respectively, if your card just has to be discarded (and is therefore largely safe from any interaction from the opponent's side prior to activation), you need to be more conservative with what it can do. There is room in the game for both of these, just understand that handtraps CANNOT be on the same Level as regular traps.

Investment directly relates to output.

I am growing increasingly sick of seeing Fusions done without Fusion Spells, or the Fusion Spells using materials exclusively from the Deck. Heaven forbid we Fusion/Ritual with materials from the hand and field only in 2021...

EPILOGUE

Look, of course making custom cards is complicated. It’s as complicated for us as it is for Konami, as it should be. Yugi is a hobby, and like all hobbies it takes time and energy to master. If there is 1 thing you need to keep from this article, that is to never make cards you would not enjoy facing yourself. It's all about enjoyment in the end, and that cannot happen when things feel cheap.