The "Legendary" rules cause problems with flip cards purely because we can't change the card's name and all flip cards have the Legendary super-type on at least one of it's sides (some have it on both sides, but with different card names).
In real magic you can have up to 4 Kitsune Mystic cards in play (more with
Clone and other card copiers), but only 1 Autumn-Tail Kitsune Sage (due to the Legendary rule).
In DotP we can have up to 4 Kitsune Mystic cards in play (more with
Clone and other card copiers), but when the card is supposed to be flipped we have to make a choice:
- Either we create a token which represents the flipped card, this can correctly handle the Legendary rule along with the new name for the card, but fails to work properly when combined with things like Clone and other card copiers.
- We "change state" on the card which works for Clone and other card copiers, but doesn't let us change the card's name. Then for the Legendary bit, we have some issues as we don't know how the game will handle a card with Legendary and one without with the same card name so we have basically three options for this:
- We add the Legendary super-type like we are supposed to and hope the game doesn't completely barf and die. If it doesn't die then I see these possibilities:
- The Legendary rule will cause you to sacrifice one or more of the other Kitsune Mystics you have in play due to one of them becoming Legendary. This is obviously a problem as the others are not Legendary and should not be removed.
- The Legendary rule will cause you to sacrifice the Kitsune Mystic that just became Legendary because it is the only Kitsune Mystic with the Legendary super-type. This is obviously a problem because we essentially would not be able to flip cards if there are more than 1 unflipped card of that name in play.
- The cards will co-exist as long as two or more don't have the Legendary super-type. This is the possibility we hope would occur as it would be the most correct.
- We don't add the Legendary super-type and we manage the "Legendary" rules manually through card code. This has the problem of causing problems with cards like Empress Galina, Day of Destiny, and Arena of the Ancients (not an exhaustive list).
- We completely ignore adding or managing Legendary super-type or rules. This is wrong because then you could have multiple "flipped" Kitsune Mystic cards which you should not be able to do.
If it turns out that option 2.1 possibility 3 happens then flip cards become a real possibility (minus name change), but I don't find that very likely. The Transform mechanic uses option 1 because
Clone and copy effects don't pose a problem with Transform cards. Level-up cards basically use option 2.3 as they don't normally change names and don't have to worry about the Legendary rule issues.