Bowser Stunner

Bowser Stunners are Amp-like obstacles 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 / New Super Mario Bros. U Deluxe
In New Super Mario Bros. U and New Super Mario Bros. U Deluxe, Bowser Stunners make their only appearance as obstacles in Red-Hot Elevator Ride, where they electrify the player upon contact. Unlike 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
In New Super Luigi U, Bowser Stunners 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.