Event · M41

The M41 Caliban Rift

The M41 Caliban Rift was a warp rift opened over the ruins of Caliban in the 41st millennium by three ancient devices acting in concert. Caliban, once home world of the Dark Angels Space Marine Legion, had lain in ruins since its destruction at the end of the Horus Heresy. No precise date within the millennium is recorded for the rift’s opening, and no fixed location beyond the ruined world itself is given. The devices responsible — Tuchulcha, Ouroboros and Plagueheart — were capable, when brought together, of tearing open a passage that bridged both space and time. Tuchulcha, the device at the centre of the episode, is held to be an ancient and sentient artefact, possibly a warp entity, of origin tied to the Old Ones. During the Horus Heresy the Lion, Primarch (one of the Emperor’s gene-forged sons) and master of the Dark Angels, recovered Tuchulcha in the Perditus System and kept it from the hands of Calas Typhon. By the Heresy’s close the device had been secreted aboard the Rock, the Dark Angels’ mobile fortress-monastery, where it lay hidden for millennia, known to only a few, including among the Fallen — former Dark Angels who had broken from the Chapter during the Heresy. In the 41st millennium the renegade known as Cypher disclosed that Tuchulcha lay within the Rock, and warned that the Fallen’s history might yet be altered if the other two devices, Ouroboros and Plagueheart, were also recovered. He cautioned that the Fallen Astelan and the Death Guard commander Typhus were seeking them as well. The three devices were eventually gathered, and together they summoned a warp rift over Caliban’s ruins. Azrael, Supreme Grand Master of the Dark Angels, moved to close the breach before nearby Fallen could pass through it and alter their own history; persuaded by the Interrogator-Chaplain Ezekiel that the past should remain unchanged, Azrael destroyed the rift. Tuchulcha was not lost in the act: it remained aboard the Rock, secured within a vault known to only a handful of the Chapter.