Sentry Buster (Canon, but with robot woman legs)

The Sentry Buster is a specialized robot that appears in Mann vs. Machine when a Sentry Gun has dealt significant damage to the robot horde. It appears as a large pair of legs similar to a female robot legs, but with a large naval mine for a torso, and it's head and arm are absent meaning, it totally doesn't have a head and arms and hands.

Once a defending Sentry Gun has reached a certain amount of kills or damage (see Spawning requirements), a Sentry Buster is dispatched; they do not appear under any other circumstances. Once deployed, the Sentry Buster makes a beeline for the Sentry Gun that triggered its appearance while making a beeping noise if you get close. Upon reaching its target, it crouches and begins beeping. About 3 seconds later, it detonates in a massive explosion.

Sentry Busters spawn against and target Mini-Sentry Guns or regular sentry guns, but they ignore Disposable Sentry Guns, even if it is doing more work than the primary one. If a Sentry is destroyed before the Sentry Buster gets there, it continues running to where the Sentry used to be and then detonates. If a Sentry dies high enough in the air (in the case of an Engineer dying midair while hauling one) before the Sentry Buster can reach the Sentry Gun, it runs around the area directly below, often giving up and detonating after a few seconds. Rarely, they may become stuck and not detonate for a few minutes, or if the team sufficiently damages it. These Sentry Busters do not prevent new Busters from spawning, and a new one spawns after the cool-down period, as long as the Engineer rebuilds the Sentry and it is not destroyed by other robots. A Sentry Buster self detonates if it cannot find a path to a Sentry Gun.

Destroyed Sentry Busters, whether by themselves or by the players, leave no credits. A large cloud of dark grey smoke lasting a few seconds remains after detonation, blocking the view of players within the range of the smoke.

The model of the Sentry Buster references the design of naval contact mines iconic to World War I and II naval warfare.

It doesn't talk, it only makes ticking noises and booming metallic footsteps when it runs and walks.