Boo Stack

The Boo Stack is a group of eighty-two Boos that appear in The Enigmansion in Paper Mario: Sticker Star. When Mario searches the mansion for Boos to trap within the Book of Sealing, he comes across a large cabinet in a room on the second floor. When Mario opens the cabinet, all eighty-two Boos that were hiding in there fall out at once, covering Mario. They then combine into the Boo Stack and engage Mario as a single enemy.

The Boo Stack attacks by dropping to the ground and rolling into Mario, an attack which deals 3 damage. Every attack Mario lands on the Stack will defeat one Boo, permanently dropping its max HP by one. Once the last Boo is defeated, the stack is bested and all eighty-two Boos are trapped within the Book of Sealing. This enemy is similar to Whomp from the same game.

Boo Stacks reappear in Paper Mario: Color Splash in the parallel versions of Lighthouse Island and Fortune Island. They appear only as a 10-Stack, and their health is represented by the number of Boos left in the stack.