Now here will show you now You start by him putting donald or goofy make sure he gets donald why ill tell you later now hit him with 3 combos make sure goofy throws his shield why because he wont trap goofy which means you can hit more now the key in the book world is to cast reflect when you start why because that way you see who is the real book just make sure you dont miss a combo because then he makes that same spell thats at the start of the book world now return nomal and jump back to paragraph one when you finish hes gonna make his DM you need dodge roll for that and head to the blue light then back to paragraph 2 And for those critical players make sure he dosent trap you in the book world cast reflect
Theres also an insanely cheap way to win the battle, which is farming for Magic Boosts until you get 76 Magic (I think you can get them from Roxas fights), equip Fire Boost and Bond of Flames, go Final Form and keep it up till he dies. I guess thats kind of a drastic "last resort" type thing, but it's still just incase you completely give up on strategies...or just wanna beat him hard.