A few pointers for designing custom cards

[Rongaulius]

Designing a balanced card is rather difficult to do, or it can be.  Designing a whole archetype of balanced cards is even harder.  Even Konami struggles to do precisely that, as evidenced by the existence of the Banlist.  A lot of the custom archetypes I see are either outright busted or too weak to be playable.  Finding the middle ground can be difficult.  These are a few things I've learned over the years through trial and error. 

#1: Avoid making 1 card too strong.  This is a common one, and one of the biggest mistakes a lot of people make with custom Yugioh cards.  One card is sometimes all it takes to turn an archetype or deck into a Tier-0 monstrosity.  One thing to further keep in mind while considering this is the next item on the list:

#2: Your deck has to contain 40 cards minimum.  One card doesn't NEED to do everything to fix the deck, and honestly, your favorite existing strategy probably only needs one or two decently powerful cards to make it work.  If you're designing a complete archetype from scratch, the same thing holds true even more; if you run 3 of most of the cards in your deck, that still means you'll be designing probably 14 cards at least.  And that's just the main deck.  There's no need to slap every good effect you can think of on one card.

#3: Speaking of which, keep card effects to a minimum.  Seriously.  Most good monster cards have one or two very powerful effects, not six.  Two carefully chosen effects are easier to read and simpler to remember than a massive wall of text for four unique effects, and two good effects from one card is still a lot.

#4: That leads directly to the next point, which is monster type, level and such.  Choosing good types, attributes and levels can be just as important if not more so than the effects.  There are plenty of cards out there in the TCG that are used for what they are rather than what their effect says they can do. 

#5: Segueing directly from proper types and attributes: If you're designing an archetype with a bunch of different types, levels, and attributes, make sure there's synergy between them.  We've all made archetypes with mind-boggling mish-mashes of levels, types, and attributes.  There needs to be a reason for those variations.  Especially if you want to include a lot of high-level main-deck monsters in your archetype.  Keep in mind that you're going to be seeing those monsters in your hand while you're playing the game, so if you have a bunch of 12* monsters, you need to be able to do something with them in your hand. That is exactly why decks like "LV" monsters tend to be very, very bad.  LV should be its own Extra Deck mechanic, but it isn't.  Designing cards that level up, evolve, or what have you is a cool idea...but Yugioh doesn't work like that in practice. What happens is that those big evolutions wind up in your hand and you can't use them.

#6: Just because a mechanic is cool doesn't mean it'll translate to being good in play, and powerful starters with a weak payoff result in a deck that just fizzles.  Your strong starters need a viable finish, and vice-versa.  Consistency equals power in Yugioh.  A deck with a high power ceiling but low consistency will almost always lose to a deck with a much lower power ceiling but good consistency.

#7: Balance and interaction are even more important in casual play than in competitive. Don't try to design an archetype or series so strong that your opponent can't hope to do anything about it.  You might as well go play solitaire if you do.  I've made archetypes that could play right through anything thrown at them, and it's not fun for either the user or your opponent.  It gets boring.  A good deck can be strong while still allowing counterplay. 

That's about all I've got for now.  Hope this is helpful to those working on their own projects.

[WhiteThunder777]

That is indeed true.  I don't design an archetype to the point where my opponent can't play.  That's just wrong.