Lorgar - Against Horus: Following the Shadow Crusade, Lorgar began to believe that Horus was too weak to lead the forces of Chaos to victory over the Emperor. He was disgusted by Horus' refusal to submit to the power of the gods, and had foreseen that Horus would ultimately lead the Traitors to defeat on Terra. Lorgar became secretly committed to killing Horus and taking his place as the Warmaster of Chaos and the anointed champion of the Dark Gods.Lorgar made his move following Horus' fall at Beta-Garmon, coming to Horus' flagship the Vengeful Spirit with one of his loyal Astartes, the Dark Apostle Zardu Layak. Though Horus was comatose, Lorgar agreed that the Traitors' needed to be assembled at Ullanor in preparation for the final drive on Terra. However, not all of the Traitor primarchs could be found nor were they all obeying the summons. Thus Lorgar proposed that Perturabo journey to find Angron while he sought out Fulgrim.Using an oracle disciple of Cyrene Valantion named Actaea as a guide, Lorgar, Layak, and a small force of Word Bearers entered the Webway in search of Fulgrim. They successfully navigated its treacherous corridors to enter the Eye of Terror where they eventually entered the Realm of Chaos and soon found themselves before the Palace of Slaanesh itself in the Dark Prince's Realm. Within they discovered Fulgrim and the Daemon N'Kari engaged in debauchery. Fulgrim refused to leave his delights and return to the war effort, forcing the two sides to battle. As Lorgar held off Fulgrim, Zardu Layak uttered the True Name of the newly ascended Emperor's Children Daemon Primarch.Layak had learned the name during a ritual Lorgar had conducted but due to the total amnesia it would eventually curse the name's bearer with, he had given the information to the Dark Apostle instead. Fulgrim was bound to Layak's will by the name's utterance, and Lorgar now had a powerful pawn with which to slay Horus. After gathering the disparate Emperor's Children together, the two Legions arrived at Ullanor for Horus' muster.Horus had by this point recovered thanks to the sacrifice of his longtime Equerry Maloghurst, and Lorgar revealed his plan to usurp the Warmaster. After sacrificing large numbers of mortal servants, Lorgar planned to unleash a psychic scream that would disorient Horus, then have Zayak order Fulgrim to attack. The Word Bearers and Emperor's Children orbiting Ullanor would finish off the Sons of Horus Legion, leaving Lorgar in total command of the Traitors' war effort.However Lorgar's coup quickly fell apart, as Actaea had already warned Horus of Lorgar's planned betrayal. Upon meeting Horus on Ullanor, Lorgar was immediately attacked before he could unleash his psychic assault, and Zardu Layak betrayed Lorgar by freeing Fulgrim from his bindings instead of ordering him to attack.Lorgar was beaten mercilessly by Horus, who threw him his weapon and demanded he stand and fight. Lorgar refused to fight, and instead expressed pity at the monstrosity Horus had become since his recovery, as Horus had gained an ever-shifting form with a maw of dark Chaos energy at its core.Horus ordered Lorgar to leave his sight, pledging to kill him if he ever returned. The 5,000 Word Bearers of the Chapter of the Unspeaking under Lorgar's command who had followed their Dark Apostle Zardu Layak in his betrayal of Lorgar would continue to serve Horus and campaign with him on Terra. Lorgar left for destinations unknown, proclaiming that Horus was doomed to failure due to his weakness.As the Word Bearers battled across the Ultima Segmentum, those of the XVII Legion led by Zardu Layak participated in the Siege of Terra, where Horus and his forces were repulsed and defeated after a fifty-five-solar-day siege. After the death of Horus, the XVII Legion ultimately took refuge within the Warp rifts of the Eye of Terror and the Maelstrom, vast wounds in space where the Immaterium leaked into reality.