General Piece-making Guidelines
I'm going to go over some rules-of-thumb for piece creation. Others may want to expand on this, as I'm sure I'll leave some things out, but I thought it might help.
1.) If you have to explain it outside of the piece description card, you should re-work it. This includes "hidden information" (which means any necessary information that is not contained within the description card) -- although there are obviously some exceptions to that, as you can't see what a piece promotes to (other than the name), for example.
2.) If you're relying on "scan order" to resolve conflicts (multiple melee Triggers, for example), this not only counts as hidden information, but makes the piece behave differently depending on which side it is on: For Black, it will favour the spaces behind the unit, whereas for White, it will favour the spaces in front of it. Which is better depends on the effect and the scenario, but the point is that the unit should not behave differently depending on who started first (particularly since that is random, which brings us to the next point).
3.) No randomness. Yes, there is ChaosPortal, which is a challenge-only, AI-use-only unit. If you're wanting to make another challenge-only, AI-use-only unit, you may ignore this rule... but even then, you probably shouldn't.
4.) CEO description cards can support approximately 11 to 13 lines, depending on how many abilities/passives are used (as the spacing is wider between abilities than the word-wrap spacing). Yes, the PieceMakers will let you get away with a lot more, but CEO won't. Personally, I hope Grand doesn't allow scrolling on the description cards -- if you need that much space to say what occurs, it either isn't a good ability or needs to be reworked. There shouldn't be any War and Peace abilities. ;)
5.) You should try to make your piece with as few different abilities as possible while maintaining the idea of the piece. 4 disparate abilities are usually the outer bounds of acceptable, though it varies (and with the way Path abilities are set up right now, a few more could be OK).
6.) Words matter. There is a difference between "move towards unit" and "move up to unit", for instance. Unless distance is specified, the first is ambiguous; the second is variable, but that variation is defined by the location of the other unit, so all information is available. Try to think about all the ways that your descriptions can be interpreted and if there is any vagueness that should be resolved. This is probably the hardest and most frustrating aspect of piece creation, so don't get discouraged.
7.) Hostage. Well, really, one should try to take into account all army possibilities, but Hostage is the big offender here: If you allow your own side a way to kill it, it makes an unfair unstoppable way to harm your opponent without recourse. This is why Hostage was made Magic/Trigger immune (Magic because of Thunder; I can't recall why the Trigger-Immune, but I'm guessing it was the ease with which one could suicide into Samurai). It also means that, unfortunately, a "remove passives" ability is not viable (something I've forgotten on more than one occasion).
8.) Promotion chains are not necessarily unviable, but they really need to be thought out. If a Minion promotes on the back row (or promotion manner is unspecified, which means the same thing for promotable Minions) and the thing it promotes to can promote into something else, the thing it promotes to can't also promote on the back row (which also means the manner of promotion must be specified). For one, it makes the second promotion absurdly easy, making the interim unit virtually meaningless. I'm not certain if it will automatically go from the first in the chain to the last, or if it would take a turn for each, but that ambiguity also violates rule of thumb #1. Note that you can have the back-row promotion on an interim unit, as long as the first one uses some other manner of promotion (e.g., kill a unit -> promote -> back row -> promote). Also note that only location-specific promotions (as far as I know) have this issue.
9.) Anything that's not (Unblockable) or (Magic) (or possibly Trigger, depending on the Trigger effect) that isn't in a direct line from the unit needs to be Pathed.
addendum/snipe.) Don't let anyone tell you that asymmetric Champions are inherently bad design. That's BS. However, it is true that they are harder to make well, so the more asymmetry you plan to add, the more careful you need to be. Also, be aware that there are many people that hate the idea of asymmetric Champions (because reasons), so don't rely on getting many votes in a piece-making contest if you do this. Call it a Minion and they'll be fine with (that part of) it (because reasons), even though it's the exact same piece.
Happy Piece-Making!
Quick note on Hostage since this turns up all the time in piecemaking: if the idea is really good for ally attack, you can just pretend hostage doesn't exist, since it is technically possible to remake hostage to conform to that new unit by having some enemy-only behavior, rather than the suggestion needing to conform onto hostage and potentially never existing in the first place because of it.
If you are aware of hostage and still want to make a suggested ally-kill type effect, you could just indicate somewhere '(except hostage)' and everyone will know you at least realized the problem in its current form.
Some extra piecemaking tips:
1 - Avoid sidegrades. If there's a reason you'd want to use a lower tier unit over a higher tier unit that doesn't consider morale or cost (Greed and Princess are acceptable despite getting worse morale damage passives each tier), it's considered dubious design at best.
2 - Consider binding carefully. Neglecting to consider that a piece that can only move on D, or can move on D or A is doublebound and can only reach 1/4th of the board and removing its binding cheaply in the next tier is something I consider a design flaw. The chessboard pattern allows you to see at a glance if a piece has at least colorbound binding, if only light colored squares have movement options your piece is at least colorbound.
3 - +5 should be considered the maximum reasonable cost increase for a champion and +3 should be considered the maximum reasonable cost increase for a minion. Anything higher is a surefire sign your upgrade is doing too much. A +6 champion upgrade (Soulkeeper++) and a +4 minion upgrade (Apprentice+++) exist, but consider those just outside the line of what's reasonable.
4 - If your piece is solely a combo piece like GravityMage, people will forget your piece exists or meme the hell out of a broken combo.
5 - Avoid putting abilities that can destroy or render unusable units on Range 4 forward or further as Unblockable or Range 3 forward or further as Magic.
speaking of hostage, once when play with AI, I move hostage into location front of AI's samurai and Samurai's passive attack didn't trigger.
It's written on hostage, it was mentioned in post, yet here we are :
Samurai - (Trigger) ...
Hostage - (Trigger-Immune)
Miyamotohishiro - (Reading-resistant) :)
MiyamotoHishiro - (Reading-Immune)
If you were immune, you wouldn't even know what's discussed here.
hostage is trigger immune
MiyamotoHishiro - (Reading-Immune)
LOL
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