Legienstrasse was the first and last "graduate" of the renegade Maerorus Temple of the Officio Assassinorum.

In combat, Legienstrasse proved to be a near god-like foe. During a confrontation in the city of Krae, Legienstrasse was able to combat Captain Lysander of the Imperial Fists, a squad of Assault Marines and 1st Company Veterans, the Imperial Fists Chapter's Emperor's Champion and a Grand Master of the Culexus Temple, while simultaneously dodging sniper fire from a Scout Squad and Grand Master Skult of the Vindicare Temple. The Culexus Master Lady Syncella was killed, alongside a number of Imperial Fists.

https://wh40k.lexicanum.com/wiki/Legienstrasse
legienstrasse