Winner's Proof

The Winner's Proof (ウイナーズプルーフ) is a Keychain for Sora's Keyblade that appears in Kingdom Hearts II Final Mix.

Sora is rewarded with the Winner's Proof after satisfying the first twelve of the Mushroom XIII and returning to the Great Maw to find the thirteenth.

Design
Winner's Proof displays exactly thirteen Mushrooms; four in the links and Keychain, two in the handle and the remaining seven on the blade, with one serving as the Keyblade's teeth. The Roman numeral XIII is shown just above the hilt and signifies the thirteen tasks you need to complete to acquire it. The head of the Keyblade forms a heart, bearing resemblance to the Ultima Weapon.

Winner's Proof's name comes from the fact that you have to pass thirteen tests, one for each Mushroom, to acquire it.

Gameplay
It is the Keyblade with the highest bonus in Magic in Kingdom Hearts II Final Mix, surpassing Fatal Crest from the original Kingdom Hearts II. When the Keyblade strikes the enemy, the symbols the Keyblade produces are flowers and small stars (some of them have the face of the Mushrooms).