Unbound

Unbound (オーバードライブ) is a Keychain for Sora's and Riku's Keyblades which appears in Kingdom Hearts 3D: Dream Drop Distance. It is obtained after clearing each "secret portal" for the respective character.

Strategy
The Unbound has the highest damage output of any Keyblade in the game, and is also the most succesful at landing critical hits and Reality Shifts. However, it is inferior to the Ultima Weapon and End of Pain in terms of magical strength.