Most of the rules that govern how transforming double-faced cards apply to the new modal variety
We'll be looking at base version of cards , essentially those you can expect to open in Play boosters
It is possible that the developers might consider adding redeem code functionality later down the future
IIRC in Yugioh there is only a certain number of Blue-Eyes (from the show?), so you could put a rule on the card 'there may only be X Blue-Eyes on the battlefield at any time', Star Wars CCG used to have permanents that you could have 2 or 3 copies of in play, in addition to stuff you could only have 1 of, the concept would work fine here too, only this could care about both players' boards
He's not food, he can't be eaten, but he's a gingerbread man
This is thankfully a lot slower than Griselbrand, and cant sustain itself