Shock troops

The Fourth Doctor identified Sontarans of the Sontaran Special Space Service who participated in the Sontaran invasion of Gallifrey as shock troops. (TV: The Invasion of Time)

Gallifreyan shock troops served in the Last Great Time War. (AUDIO: The Rulers of the Universe)

As observed by the Eleventh Doctor in an alternate timeline, the cyber-converted Judoon served as the Cybermen's shock troopers, mindlessly destroying everything in their path. (COMIC: Assimilation²)