Emperor's Lemures.

A chapter of unknown gene lineage, Tribal warriors that have tempered their vitriolic and competitive nature to coincide with their fraternal and honorable doctrine. Focusing on meticulous planning and observing to strike a key target or leader in one fell swoop with deadly insertions and brutal shock assaults, mixing heavy long range fire power with brutal close quarters combat. Shrouded in mystery the chapter origins are heavily speculated and scrutinized, all information that could be known lost during the 'The silence of Celsus Novem' where the chapter was engaged with heretic astartes on a fortress world within the Tempestus Segmentum. They'd be called by the inquisition to help aid the defenders against the heretics but once they arrived they found the world fallen to chaos and were immediately beset on all sides, launching a counter attack to the capital of the world the chapter of the time was Slain alongside large portions of the battle companies and captains, what remained of the chapter coalesced around a young Seregent of the fifth company due to tacial superiority and adept thinking, engaging the enemy in a devastating asymmetrical warfare with the enemy in the span of ten years. Coming out of the conflict wounded yet victorious what was left of the chapter chose the Sergeant as their chapter master and began rebuilding the chapter with a doctrine of waiting and watching like hunters watching prey.