Armageddon Prime fell swiftly to the Chaotic army, and the survivors fell back and prepared to make a last ditch stand along the Rivers Styx and Chaeron. Unknown to Angron, several Great Companies of Space Wolves Space Marines led by the Great Wolf Logan Grimnar himself had arrived to bolster the Imperial defence. Titanic battles erupted all along the front as the Forces of Chaos crashed into the Imperial line. It was at this moment that Logan played his trump card in the form of a full company of Grey Knights. Only the Grey Knights could deal with an entity as powerful as Angron, and after a desperate battle they were able to hurl his spirit back into the Warp. Without their leader, the Forces of Chaos were routed and Armageddon saved.