|Chapter Master||Lord Magyar|
|Homeworld||Bascilica Mortis, orbiting Posul|
|Specialty||Tribal Savages / Night Fighting|
|Allegiance||Imperium of Man|
|Colours||Black & White (specifically Bone whites)|
The Mortifactors are a Primogenitor Chapter who REALLY do not get on with their forefathers, despite the fact that they follow the codex and are the second sons of the XIIIth Legion. Also they can be total dicks, leaving their allies if they don't feel like fighting for something that matters.
The differences between them are mostly cultural rather than doctrinal, and (like the Fenrisians) is more a result of the homeworld they decided to inhabit than anything else.
Posul is the stereotypical savage world, almost completely dark due to having a thick, smoky atmosphere, and is populated by cannibalistic tribal warriors who constantly wage war upon one another. This is probably contributed to by the fact that any night world will have little to no plant life, so the population would have to become carnivores by necessity, and like any world in the Imperium, humans are rarely in short supply. Never mind that this really wouldn't work because carnivores are far less energy efficient than herbivores or plants. And never mind this wouldn't work since ecosystems have to have producers at the bottom anyhow, and meat-eaters are just getting those nutrients secondhand. Posul probably had more fungus than plants, but the name of the bottom-producer doesn't particularly matter here.
Their chapter Fortress-Monastery is a massive space station that orbits the planet. Its halls are filled with rows of engraved skulls, the final resting place of fallen brothers - while the chapels and shrines of the chapter are filled with the skulls of enemies who have been defeated.
Very peculiarly, the Chaplains of the Mortifactors are chosen exclusively from the shamans of Posul, which is probably a massive contributory factor to the behaviour of the chapter. Their typical rites involve copious amounts of blood-letting and shared blood drinking, where the enhanced physiologies of the Astartes will interpret the combination of visions to determine future battle plans.
Furthermore, once a battle has been won, they will go amongst the fallen enemies and consume portions of their flesh (presumably where it is safe to do so) before collecting the skulls of worthy foes to return to the chapter. To outsiders this makes them little better than extreme savages at best and outright Heretics at worst. (Of course, the Omniphagus organ that space marines possess allows them to gain tactical information from feeding on fallen foes. While few chapters do so as openly, fewer still are the chapters that do not partake at all.)
Apparently, they had very little contact with the other Primogenitors, being generally treated with suspicion but little outright antipathy. The full extent of their differences only really came to light when Uriel Ventris fought alongside them against the Tyranids, much to the disgust of the Ultramarines. However on that occasion the Mortifactors had the backing of the Inquisition and so nothing was settled between the chapters.
Lastly, their current Chapter Master is Lord Magyar ("Magyar" being the Hungarian word for, well, Hungarian). Lord Magyar is noticeable for wearing artificer armor crafted entirely from bones. He also carries a war scythe and features a winged skeletal familiar perched atop his throne. Most Astartes estimate Lord Magyar to be around 700 years old, but nobody is really sure. In short, this guy knows how to reap a bountiful harvest of death, and has the gear to show for it.
Another notable figure from the Mortifactors chapter is Watch Captain Artemis.
One controversial relic the Mortifactors owned was Roboute Guilliman's combat knife, though it remains unknown how they came to possess it. It caused them no end of trouble because the other primogenitors would protest that such deviants were holding a relic of their primarch.
It was only when the Lord of Macragge interceded that the Mortifactors gave up the relic. But rather than surrender it to the Ultramarines or any other descendant of Guilliman, they trolled the Ultramarines by entrusting it to the Deathwatch for safe-keeping instead, where it might be still used by Mortifactors who swear oaths to the Ordo Xenos.
In a bit of strange, f**ed up idiocy, Posul was declared as having been destroyed by Hive Fleet Leviathan as of 997.M41. This would mean the Mortifactors lost their home-world only a year prior to their largest deployment. With their fielding of all 10 companies in 998.M41 at the Third War for Armageddon, it begs to be asked if perhaps the Chapter had resigned themselves to a glorious death on the fields of battle rather than restore their chapter and continue fighting for the Emperor. On the one hand, it would make tons of sense if this were the case, as the Mortifactors have a very strong set of beliefs regarding the afterlife - namely, that their dead get to feast with "the Ultimate Warrior" (a divine being that inhabits the perfect body for fighting prowess, which could very well be the Big E pre-Heresy (or maybe he is that other Ultimate Warrior)) in the Hall of Victors. On the other hand, these dates are always subject to some revision, thanks to Games Workshop's dubious stance on canon consistency.