Obsidia

Obsidia is a fortress-world that belonged to the Astral Knights until their destruction and was afterwards granted to the Sable Swords.

The Astral Knights were destroyed while preventing a Necron World Engine from completing its purpose. Following their loss, the High Lords bestowed the world’s keep and fief upon the Sable Swords, who had been newly raised. At a later date the Novamarines relieved the planet after mutants of the Twisted Convocation threatened it.

Obsidia’s recorded history thus comprises the fall of its original defenders, the establishment of a successor force in their place, and a subsequent rescue by a third. The world is not a Black Templars homeworld: the Black Templars are a fleet-based force and hold no fixed planetary seat there.