Mortanis

Mortanis is a notable death world that serves as an Adeptus Astartes homeworld of the Ultima Founding Feral Sons Space Marine Chapter.

Background
Mortanis is a Death World and also the homeworld of the Feral Sons. There are scattered forests of vertical dark green sheets of plant matter. The land is a maze of steep valleys. The animal life on this planet is a kind of protoplasmic ooze capable of temporarily forming itself into myriad shapes. The planet is home to extremely dangerous apex predators, leathery brown creatures that move faster than the eye can track. They have multiple heads. Many moons can be seen in the sky. The uncounted tribes of the planet are in a never-ending war against one another.

Fortress Monastery
Like all Astartes fortress-monasteries, Feral Menace is armoured and void-shielded to withstand any siege or bombardment that might befall it. Armed to repel attackers from land, air or space, its walls bristle with enough heavy ordnance to flatten a hive city. Every aerial approach to the fortress-monastery is overlooked by Icarus Pattern Lascannons, and a Macro-laser known to the Feral Sons as Dorn's Rage stands like a spear of vengeance to lance space-borne enemies from the heavens. The fortress-monastery's Librarius is a lightning-wracked spire where the Chapter's Librarians study their lore and chronicle the deeds of the Praetorian. They also preside over the Chapter's Astropaths as they relay psychic messages throughout the void, communing with the greater Imperium and those Feral Sons Battalions hunting across the galaxy.

The Feral Sons live apart from their people, descending down to the jungles only once in a standard decade to observe the wars between the tribes and to choose potential recruits for the Chapter. The constant warring ensures that the people remain strong, though the Feral Sons have to be vigilant that such feuds are not retained as recruits or recruit initiates.