The Shard of Tartarus

 

A major portion of Alpha Legion and Stygian forces were diverted at the behest of Abaddon the despoiler. The ark of omen known as The Shard of Tartarus was offered to them if they could claim it.  The Alpha Legion committed nearly a 150 marines, 50,000 Stygian infantry, a full ten divisions to the clearing of the hulk.  In addition nearly 20,000 cultists and mutants were unleashed along with a strong detachment of the Dark Mechanicus sworn to the 7th Hydra company of the Alpha Legion.

With this influx of forces a very bloody and costly campaign began for control of the ark.  Many genestealers were to be found aboard and needed to be eradicated.  The genocidal determination of the Alpha Legion matched that of the time of the great crusade and so at a cost of nearly 12,000 mortals the genestealer menace was eliminated.

The remaining threat came from warp entities and other denizens of the warp preying on any who entered their corridors.  Another 15,000 followers were to perish to the warp gheists that infected the space hulk.

With sorcerers and masters of possession able to coral the warp entities temporarily the Dark Mechanicus established control over the ark and prepared a strike in the Stygian sector on behalf of Abaddon and Vashtorr.