Sentry Busters

Overview
"Essentially a bomb on legs, the Sentry Buster will detect any sentry that’s dealing sustained damage to the Robot Horde, then initiate its deviously complicated protocol: run at the offending sentry and explode."

— Mann Vs. Machine publicity blurb

A sentry buster is an enemy encountered in MvM. They are a spherical bot which walks on two legs with spikes on their head. When spawned in, they will target a dangerous Engineer and blow their sentry up.

They will not be spawned in if there are no engineers on the map. They will also not be spawned if an Engineer's sentry hasn't gotten around 3000 damage/15 kills.

The team will be notified of the Sentry Buster's arrival; the administrator says this:

"ATTENTION ENGINEERS! We've got a sentry buster!"

"Alert! A sentry buster has entered the area!"

Sentry Busters will only target the sentry they are dispatched for and will not attempt to kill any other players. But players can damage the busters and make it explode earlier than it was supposed to. Players can be killed by the sentry buster.

Sentry Busters appear in every mission.

Strategy

 * When a sentry buster spawns in, there is a loud ticking noise that plays. Engineers that are stupid will let the busters take down their sentry.
 * You can use the Rescue Ranger to place your sentry else where, stand back, and when the sentry buster taunts, haul it to you from far away and run.
 * If not, pick up the sentry and run away from your buildings or than into the buster when far enough, than run away from the buster.

Sentry Running
When a sentry buster spawns in a good ability for Engineers to know is how to get it away safely in the head of battle.