Rubric of Ahriman

The Rubric of Ahriman was an immensely powerful spell cast by a cabal of Sorcerers from among the [{Thousand Sons]] Legion led by the Sorcerer Ahriman.

This cabal had been repulsed and terrified by the rampant mutation among the Thousand Sons after their escape into the Warp, and cast the Rubric to halt this terrible plague. They summoned an immense storm that engulfed the Planet of the Sorcerers, and from within came bolts of lightning that struck down any of the Thousand Sons without psychic talent. Their bodies were disintegrated into ash, and their souls lingered in their now sealed armor. They were mindless automatons, only fit to do as ordered.

Magnus the Red, Daemon Primarch of the Thousand Sons, summoned the cabal before him and berated them for their foolishness. He raised his immense fist to strike down Ahriman, but then Tzeentch whispered to him "Magnus, would you destroy my pawn so easily?" To avoid disrupting his master's plans for Ahriman, Magnus sent the Sorcerer on a quest to understand the nature of Tzeentch and the Warp.

Since then, Ahriman has wandered and the Thousand Sons have marched into battle led by apprentice Sorcerers, who are the only ones able to control the mindless beings that now lurk within the armor of the once-proud XV Legion.