A Creepy Ball
From the Super Mario Wiki
A Creepy Ball is a level in Bowser's Castle in the Bowser Jr.'s Journey mode of Mario & Luigi: Bowser's Inside Story + Bowser Jr.'s Journey.
The level has four battles. The first battle has five Swoops, two Dry Bones, and a Tail Boo first officer and captain. The second battle has four Boos, two Dry Bones, one Big Boo, and a Boo first officer and captain. The third battle has four Tail Boos, two Dry Bones, one Bomb Boo, a Big Boo first officer, and a Dry Bones captain. The fourth and final battle has six Dry Bones, one Big Boo, and a Malatone-infected Big Boo captain.