Regulus

Regulus was a Dark Mechanicum magos who served as Warmaster Horus’s envoy to Mars and was killed by Kastigan Ulok at the Wrought. The Dark Mechanicum was the faction of the Adeptus Mechanicus that sided with Horus. Regulus judged the Warmaster preferable as Omnissiah, the Machine-God of the Mechanicum’s creed.

Regulus opened the channels that Kelbor-Hal required for the spread of scrapcode and for civil war on Mars. He acted as both diplomat and saboteur. He also sought Standard Template Constructs (STCs), which he valued as weapons rather than as preserved relics. Kastigan Ulok, an Iron Hands warrior, killed him at the Wrought, by which time Regulus had already betrayed the Red Planet.

Regulus was a native product of Mars whom Horus employed against it. He died as an individual traitor magos, and the Wrought closed his record with a bolt round. That end fell short of what Kelbor-Hal had promised his envoys.