The Cult of the Star Saviours is a Genestealer Cult that took over the world of Evergrind some time in the 40th Millennium.
Robbed of both its Genestealer Patriarch and Magus after a pinpoint strike by the Imperial Navy, the Cult of the Star Saviours misreads a solar-week-long meteor shower as a sign of imminent salvation. Taking the shooting stars in the skies of Evergrind as confirmation that celestial rapture is close at hand, the self-proclaimed "Last Hierarch," Primus Adamant, puts into motion his plans of conquest.
On the night of the grand insurrection, every breeder city and dust farm upon Evergrind's surface is lit by the fires of revolution as the cult insurgency rises to impressively destructive heights. The cult's ascendance is like a flame to dry tinder. Riots break out in every quadrant as the local citizens take the opportunity to loot, kill and burn, exacting revenge for endless Terran centuries of oppression by their taskmasters.
During the fighting, Primus Adamant is slain by an entrenched heavy weapons team, and with his demise the cult loses much of its cohesion. By the time the new moon rises, the planet has devolved into a post-apocalyptic bedlam populated by warring tribes, lone scavengers and scuttling half-xenos predators. Those craft whose captains are foolish enough to make planetfall upon Evergrind are soon brought low and claimed by the leaderless and atavistic cult -- and the ships' passengers with them.
- Codex: Genestealer Cults (8th Edition), pg. 36, "The Lost Hierarch of Evergrind"