Final Fantasy VI Randomizer

Why not? You may risk to make collapse the game, but what if a phantom Mog wanna possess final Kefka in the name of the peace?

Ps. you may actually have 2 possess per game: one in WoB and one in WoR... perhaps Gau could possess endlessly... just recruit him at the Veldt after you use possess

Actually, if your character is on the airship, Possess will just send them back there. You can use Possess at any time you want, as long as it's not before a cutscene that a character is expected to be in (and as long as you're willing to give the character up for the rest of the dungeon).