Ball 'n' Chain as seen in Reflection Fortress.
A Ball 'n' Chain is a spiked ball on a chain swinging on a pivot. Many are found in the castles and fortresses of Brutal Mario. Touching the spiked ball will result in damage. Luckily, Mario can stand on the brick in the center to avoid being hit by the ball and using a Spin Jump will allow Mario/Luigi to harmlessly bounce off the spiked ball. The only way this obstacle can be defeated is using a star, but it will pop up a defeated Bony Beetle because it was never programmed for invincibility to defeat it.