Power Rush

Power Rush is a badge in Paper Mario and Paper Mario: The Thousand-Year Door. In Paper Mario, it is found in Peach's Castle, inside of the castle's library between a couple of shelves; it can be obtained either by Mario or by Princess Peach, who can send it to Mario via a mysterious chest (which Mario can access from a chest at Shooting Star Summit). In Paper Mario: The Thousand-Year Door, it can be bought from the Lovely Howz of Badges in Rogueport for fifty coins, bought from the Pianta Parlor for thirty-four Pianta Tokens with the Gold Card, or rarely held or dropped by Paratroopas and Shady Koopas. If Mario equips it, when he enters the Danger state (which occurs when his HP reaches five points or less), his attack power increases by two. This badge works alongside others that activate when he is in Peril or Danger, such as Last Stand and Mega Rush. Power Rush P has the same effect, but works exclusively on Mario's partner.

Merluvlee's prediction in Paper Mario

 * "I see...a Power Rush Badge. In Peach's Castle, way up in the sky, there's a room with bookshelves. The Badge is on the floor between the shelves."