Quote Originally Posted by Kraco View Post
That second Persona was a big deus ex machina. I don't know how the game pulled that off, but it would be a lot more believable if the people had some affinity to their Persona, and especially any extra Personas. For example, this Jack O'lantern seemed to be all about fire, so Yuu having had something significant to do with fire would have made it better. Now it's like he wandered a dungeon in some cheap 80's adventure game and picked up a random power up allowing switching to another Persona.

Although I reserve the right change that opinion if the opening scenes with the devilish dude and the icy secretary actually mean these "players" are selling their souls to use the Personas and accepting an extra Persona (out of nowhere) draws the due date that much closer.
The power to summon different personas was always his, that's what Margaret meant when she said he had the power of wild. The fact that he used jack was simply because the enemy's element was ice, weak to fire.