Well, I am at the end of the world, and I can't seem to be able to beat Chernabog, that demon-esque creature from fantasia. My stats look something like this:

Sora: Lvl 52, Key Blade: Oblivion
Donald: Lvl 52 Staff: Lord Fortune
Goofy: Lvl 54 Shield: Genjii Shield

He always kills me with the one move where he conjurs up a huge wave of fire. He's kicking my ass pretty badly, please help.