The Rubric of Ahriman was a cataclysmic end to the existence of the Thousand Sons Legion within the Imperium of Man. When the Emperor of Mankind neared completion of the Primarch Project in the late 30th Millennium, he enhanced the psyker genes that existed within one of the nascent Primarch zygotes he had genetically engineered. The being that would be known as Magnus the Red became self-aware during his gestation, and even managed to have some limited psychic contact with the Emperor before the 20 Primarchs were spirited away and scattered across the galaxy through the Warp by the Ruinous Powers. The Emperor was greatly pleased by this, as he thought that at least one of his sons would be a potent psyker and would be able to share some of the burden he bore as humanity's chief psychic pr