|This article is about the Artifact; for the Hive Fleet, see Hive Fleet Ouroboros.|
The Ouroboros is a mysterious possibly Chaos-related artifact that was found on Caliban during the Horus Heresy. A sentient Warp device and a sister to the Tuchulcha and a third unnamed engine, the Ouroboros helped corrupt the Dark Angels Librarian Zahariel into becoming one of the Fallen. Zahariel claimed that the Ouroboros was a manifestation of Caliban itself.[1a] The Ouroboros was hated by the Watchers in the Dark of Caliban.[1b]
Much later in the 41st Millennium, Cypher revealed that the Ourobors was acquired by Typhus and Astelan in attempt to unite it with its sister devices and change history. Eventually all 3 devices were gathered and a warp rift was summoned over the ruins of Caliban. Convinced by Ezekiel to leave history be and trying to prevent nearby Fallen forces from accessing the rift first, Azrael destroyed the rift and presumably the three devices.