You have to have a lot of zeros cards in your deck. Don't focus on the magic and summon cards because they're practically useless. Try to round your deck off with strong keyblades with level 9, 8 , and maybe a couple 7's. And definately have some Cure or Cura cards in your deck!!Maybe two clouds, but three, that's pushing it. I beat the game with patience, so just stay cool and get those good cards. I have to warn you though, be prepared for Larxene, she is one tough cookie.