After the surprise attack on Calth, World Bearer failed to destroy the Veridian System, and their commander, Kor Phaeron the black cardinal is mortally wounded by Roboute Guiliman and managed to use sorcery to escape to his flagship Infidus Imperator. Roboute Guiliman ask Marius Gage, Chapter Master of the First Chapter of the XIII Legion to hunt down the traitors responsible for the death of countless civilians and XIII Legion battle brothers.
Kor Phaeron was brought back to life with the help of his crew and the genetic argumentation. He planed on killing the Macragge's Honor's crew by summoning his daemonic allies, and then lead them into the warp where his dark gods masters. However, the Ultramarine eventually crash the Infidus Imperator. Kor Phaeron and his crew managed to fleed to the Eye of Terror via warp-sorcery and leaving Macragge's Honor wander aimlessly in the warp