From the Super Mario Wiki, the Mario encyclopedia
The Ally Tambourine is an accessory in Paper Mario: The Origami King. It takes on the appearance of a small tambourine, emblazoned with one of Mario's gloves curled into a fist. Unlike the other accessories in the game, it is not sold exclusively at any one shop, but can instead be purchased anywhere after a certain point in the game's story. If Mario equips it, it will temporarily raise the attack power of his partners in battle.
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