The Nemesors played a role in the Indomitus Crusade under Lord Commander of the Imperium Guilliman's orders and were seen in action upon the world of Agrathane Excellia by the twisted Heretic Astartes and former Emperor's Children Apothecary Fabius Bile.
Bile was so impressed with the Primaris Marines' performance in combat that he soon began planning to capture several and begin his own experiments upon them to create new versions infused with the essence of Chaos.
- Battle of Agrathane Excellia (Unknown Date.M42) - The deranged fleshmaster Fabius Bile was upon the world of Agrathane Excellia when he witnessed a strike force of Primaris Space Marines in action. Attacking from above, a strike force from the newly founded Nemesors Chapter took a fortified Black Legion bastion complex in a solar hour. Impressed despite himself, Bile developed an obsession with the capture and dissection of these statuesque warriors. His intent was to blend them body and soul with the dark energies of Chaos in order to breed his own twisted versions of Primaris Space Marines.
The Nemesors' Chapter colours are currently unknown in Imperial records.
The Nemesors' Chapter badge is not currently listed in Imperial records.
- Codex Heretic Astartes - Chaos Space Marines (8th Edition), "Pinnacles and Nadirs - The Primogenitor Primaris," pg. 48