Ahzek Ahriman

The Heresy

Ahzek Ahriman was Chief Librarian of the Thousand Sons during the Great Crusade and the closest of Magnus's lieutenants. He survived the Burning of Prospero, escaped into the warp with his primarch and the rest of the Legion, and watched as the flesh-change — the gene-instability that Magnus's sorcery had been holding at bay — began to tear his brothers apart in earnest in the years after.

When the Legion's situation became survival-or-ruin, Ahriman did what no other Thousand Sons sorcerer dared. He cast the Rubric.

The Rubric

The Rubric of Ahriman was a ritual of unprecedented complexity, designed to lock the Thousand Sons permanently against further flesh-change. It worked.

It worked too well. Most of the Legion's battle-brothers — those whose psychic gift was minor or absent — were reduced to dust held inside their power armour by sorcery, animated bodies without souls or personalities. Only the senior sorcerers, Ahriman among them, retained their consciousness.

Magnus, when he understood what Ahriman had done, exiled him. The exile continues.

I saved them. They became dust. I will undo what I did. I will. I will.

— Ahriman, attributed

The Exile

Ahriman wandered the warp for centuries, gathering Tzeentchian sorcery-knowledge that the Thousand Sons had not been able to recover. He founded warbands. He betrayed them. He pursued one promising sorcerous lead after another, hoping to find the reversal of the Rubric — the ritual that would restore his brothers and discharge his guilt.

Nothing has worked. Every reversal has failed at the same kind of failure point, by which Ahriman has begun to suspect Tzeentch himself is the gatekeeper.

Modern Activity

In the Era Indomitus Ahriman remains the most-feared mortal sorcerer in the galaxy. His knowledge of warp theology rivals or exceeds Magnus's. He is rumoured to have stolen from the Black Library, to have walked the Webway, to have collaborated quietly with both the Inquisition and with daemon-princes when his project required.

The Thousand Sons are no longer his Legion. The Rubric is still active. He works.

Pre-Rubric Position

Ahriman was Chief Librarian of the Thousand Sons before the Rubric — the second-most-powerful psyker in the Heresy-era Imperium after Magnus himself. His personal psychic-discipline framework, which the Thousand Sons called the Corvidae path, specialised in precognitive divination at scales no other Heresy-era Librarian could match. By the surviving Thousand Sons records, he had personally trained approximately 70% of the Legion's senior Librarian corps before the Heresy began.

His pre-Rubric relationship with Magnus was unusually close even by Thousand Sons standards. Magnus had personally selected him as Chief Librarian in approximately 880.M30 and had granted him direct access to the Legion's most-classified theological texts. The arrangement gave Ahriman the institutional knowledge to attempt the Rubric without Magnus's authorisation — knowledge that no other Thousand Sons officer possessed.

The Specific Rubric Failure

The Rubric's specific failure pattern was, by Ahriman's later classified internal correspondence, the consequence of two factors. First, the Rubric's psychic-engagement requirements exceeded what Ahriman could sustain personally without Magnus's specific psychic support — and Magnus had explicitly refused to provide that support. Second, the Legion's gene-seed instability had progressed further than Ahriman's pre-Rubric assessment had concluded; the flesh-change had already begun in approximately 90% of the Legion's surviving membership.

The combination produced the outcome: the flesh-change was halted (Ahriman's intended effect), but at the cost of converting most of the Legion into the Rubric Marine sustained-armour-shell biological-form (the unintended cost). The 10% who retained their physical bodies were the Legion's senior Librarian corps — Ahriman's specific apprentices, whom he had inadvertently shielded from the Rubric's worst effects through his own pre-Rubric training. They went into exile with him.

M42 Operational Pattern

Ahriman has, in the Indomitus era, returned to operational engagement against Magnus's Tzeentchian doctrine. His specific objective, by classified Imperial Cult intelligence, is the recovery of the Black Library's archive on the original Rubric — a archive Ahriman had been studying during his Heresy-era preparations but never had the operational opportunity to fully extract. The Black Library is in Cegorach's hands; Cegorach has not granted Ahriman access.

The pursuit has been operationally costly. Ahriman has lost approximately 30% of his exile-cohort across the post-Rift years to engagements with Cegorach's Harlequin troupes and Sortiarius-based Magnus-loyal Thousand Sons. The losses have not deterred him. By the most recent classified Aeldari Farseer council assessment, Ahriman is "approximately seven engagements away from gaining access to the relevant Library archive." Cegorach has not commented on the assessment.

The Library does not open for thieves. I will be patient.

— Ahriman, intercepted Tzeentchian correspondence