Summarize the following:
10. Go to Isla de Muerta in Port Royale (Pirates of the Caribbean world.) Head inside the cavern and keep heading forward until you reach the Moonlight Nook; this is the area before the boss room (where you fought Barbosa). This keyblade will help you deal more damage by letting you bypass the 2nd normal combo and immediately letting you chain 2 finishers.

Summary:
Find Mushroom no. Equip Rumbling Rose.