Severian - Severian was an Astartes of the 28 th Company who was incarcerated in the prison of Khangba Marwu on Terra after the outbreak of the Horus Heresy. Severian escaped from the prison along with several other Astartes of the Crusader Host. Severian was last sighted in the Petitioner's City on Terra and his ultimate fate remains unknown.

Lorgar and his Word Bearers originally came from Colchis, a world defined by religious fanaticism. They had long worshiped the Emperor as a god. The Word Bearers had sought to spread their Cult of the Emperor to every world they added to the Imperium. But the Emperor deeply disliked and mistrusted organised human religion, blaming it for much of the darkness that had plagued humanity's history. Horus - Horus, also known as Horus Lupercal, was the primarch of the XVI th Legion and served as the first Imperial Warmaster during the Great Crusade. Once the most favoured son of the Emperor of Mankind, he ultimately became the greatest Arch-Traitor in the history of Mankind when he turned from the Emperor's light and led half the Legiones Astartes in a galaxy-wide rebellion known as the Horus Heresy. Ultimately, this rebellion failed when the Emperor confronted Horus at the climactic Battle of Terra aboard his flagship Vengeful Spirit in mortal combat and killed him, which left the Emperor gravely wounded. This would result in his ten millennia internment within the life-sustaining prosthetic device known as the Golden Throne. However, following their corruption by Chaos, the Sons of Horus Legion's Space Marines started to exhibit random genetic mutations, and it is likely that this taint now affects their gene-seed as it has almost all of the Traitor Legions. The regular practice beginning in the Horus Heresy amongst the Legion's Astartes of seeking daemonic possession may also have accelerated the effect.Keylek Genocide (923.M30) - Early in the Great Crusade the Luna Wolves fought against the hostile alien reptilian race known as the Keylekid on the world of Keylek, ultimately wiping these reptilian xenos from the face of the galaxy. This was a long, brutal and miserable genocidal campaign that was fought long before Horus was made the Imperial Warmaster. At this time Horus was referred to simply as "The Commander" by the Astartes of his Legion.

As a result, Cthonia had been colonised, built upon, tunnelled and mined since the dawn of human interstellar space travel millennia before the beginning of the Dark Age of Technology. Due to this unusually long period of exploitation by Mankind, all of the world's natural resources had been stripped away and used up centuries before, and the ancient mining technology had long since been rediscovered and removed by the Tech-adepts of Mars. The planet that remained was largely useless and abandoned, completely riddled with catacombs, crumbling industrial plant and exhausted mine-workings.Horus at first refused, fearing that to so set himself above his primarch brothers would lead to factional strife. Eventually he did institute this change, at his bother Sanguinius' urging, just prior to the events culminating in his conversion to the service of the Dark Gods of Chaos on the world of Davin.