So apparently to get this I need to unlock a level 55 coliseum battle, but it's not appearing. I've done all of the battles up to level 62 and I did the level 40 fight with Shiva and Ifrit. I'd rather not have to imprism the level 40 Shiva because I just want to transfigure my Mishiva instead. I'm at Chapter 21. Anyone know how to do this?