The Cult Tendricul is a Genestealer Cult that originally infested the space station of Delugen but eventually spread to new worlds despite the intervention of the Craftworld Aeldari. In time, the cult even infected Aeldari space.
A strike force of Black Guardians from Craftworld Ulthwé descended upon the gyroscopic space station of Delugen. The prophetic Farseer Anathroelle Starseeker led her warriors into Delugen's corridors. There they slew the Cult Tendricul in the most thorough fashion, putting every human they find to the sword whether they were infected by the xenos taint or not.
The station's astropathic distress signal reached a Black Templars fleet, and whilst the Asuryani were rooting the last of the humans from the station's corridors, the Boarding Torpedoes of the Space Marines struck home.
The Ulthwé force was driven off, and the last few survivors of Delugen escaped. Within a Terran year, however, the symbols of the Cult Tendricul were seen on a dozen planets, including the Aeldari Maiden World of Virgose.
- Codex: Genestealer Cults (8th Edition), pg. 36, "A Doom Unstoppable"