Bowser Stunner

Bowser Stunners are an Amp-like obstacle that first appear in New Super Mario Bros. U. They return in New Super Luigi U and New Super Mario Bros. U Deluxe. As their name implies, they resemble Bowser's head.

New Super Mario Bros. U
In New Super Mario Bros. U, Bowser Stunners make their only appearance in Red-Hot Elevator Ride as obstacles, where they electrify the player upon contact. Unlike common Amps, Bowser Stunners have special chains connected to another Bowser Stunner, creating a stream of electricity to travel on the chains.

New Super Luigi U
The Bowser Stunners reappear in New Super Luigi U, and act the same as they did in New Super Mario Bros U. They appear in the Peach's Castle level Current Event where they are a major obstacle.