The all-female Assassins of the Officio Assassinorum's Callidus Temple are the most subtle of the Imperium of Man's secret operatives, specializing in deceit and the use of artful deception to accomplish their objectives, usually assisted in their bloody tasks by the shape-changing Polymorphine drug.

https://warhammer40k.fandom.com/wiki/Callidus_Temple
callidus assassin