Maerorus assassins were designed to be living weapons, able to kill masses of people with no weapon except their own bodies, since even the finest and most carefully maintained weaponry was subject to failure. Their modus operandi was to enter into a target-rich area, typically a meeting or gathering and kill every sub-target present as quickly as possible.

https://wh40k.lexicanum.com/wiki/Maerorus_Temple
maerorus assassin