Sortiarius

Sortiarius is a world within the Eye of Terror that served as the refuge and stronghold of the Thousand Sons Legion after Prospero’s fall.

Following the destruction of their home world during the Horus Heresy, Magnus the Red led the surviving Thousand Sons into the Eye of Terror, where the Legion settled upon Sortiarius. There, diminished in number and increasingly afflicted by a degenerative mutation known as the Flesh-Change, the Thousand Sons sought under Magnus’s rule to preserve what remained of their martial and sorcerous traditions.

Sortiarius is most closely associated with the casting of the Rubric of Ahriman, the working by which the Chief Librarian Ahzek Ahriman transformed the majority of his Legion into the animate, soulless Rubric Marines. The planet has since endured within Thousand Sons lore as a haunted seat of ritual and sorcery, its character shaped by the warp’s proximity and by the Legion’s continuing pursuit of a means to restore its lost brethren.