Event · M31
The Destroyer Plague
The Destroyer Plague struck the Death Guard aboard the Terminus Est while the fleet was becalmed in the warp. No year is recorded. Calas Typhon had rejoined Mortarion at Ynyx after the primarch purged that loyalist world, and Typhon then undertook to lead the fleet to Terra without Navigators, having had them executed; Erebus had told him the time was right. The plague struck once the fleet was becalmed, and aboard the Terminus Est Mortarion struck Typhon down. Ignatius Grulgor strangled him, Typhon revived, and Grulgor’s body dissolved and merged with his own, so that he became Typhus, Herald of Nurgle and host of the Destroyer Hive.
See where The Destroyer Plague occurred on the galactic map during the Horus Heresy.