Changes

While crusading with [[Lion El'Jonson]] against the [[Sarosh]] [[Xenos]], he discovered a bomb aboard the ship which would kill the Lion. Initially his jealousy encouraged him to leave it onboard and let the Lion die, however his better nature kicked in and he disabled it, with the help of the Librarian [[Zahariel]], saving the Lion's life.{{Fn|4}} However somehow the Lion discovered his hesitation, and the two had a falling out. Luther also deployed forces alongside [[Horus]] during a campaign in the Zaramund System, which resulted in him being scolded by the Lion for insubordination.{{Fn|6a}} Because of these factors, Luther was ultimately left to manage affairs on Caliban while the Lion waged the [[Great Crusade]]. Luther had to deal with [[Unrest on Caliban|a rebellion]] by the disgruntled nobility of Caliban who had their peasant farmers and lands confiscated by the Imperium. A cabal of [[Chaos]] [[Sorcerer]]s also infiltrated Caliban to bring further instability, and Luther was made aware of Caliban's possible [[Warp]]-infestation. Luther became convinced that Caliban would be destroyed by the [[Emperor]] as soon as this was discovered and became paranoid that the Lion had deliberately kept this from him as a death sentence. His superstitions were furthered when he learned that a cult of Terrans were in the process of a daemonic ritual, which was narrowly stopped by [[Zahariel]], a librarian who Luther had grown fond of.{{Fn|3}}

After turning against the Emperor, the political situation on Caliban remained tense and unstable. Luther was saved from a pro-Imperial conspiracy thanks to the efforts of Astelan and [[Galedan]].{{Fn|5}} He nonetheless drew increasingly distrustful of his primary advisers, Astelan, Zahariel, and the Lord [[Cypher]]. He became increasingly drawn to lore regarding the [[Ouroboros]]. Later, Luther met the newly arrived Chapter Master [[Belath]] on Caliban, but was forced to massacre much of the delegation when Astelan initiated hostilities against them. Lord Cypher was killed in the chaos, and Luther elevated Zahariel to the position. Later, Luther was seen welcoming a [[Death Guard]] fleet under [[Calas Typhon]] to the [[Zaramund System]], which his own forces had just attacked.{{Fn|6b}}

Regardless of the truth, when When the Lion returned to Caliban after the [[Horus Heresy]], Luther attacked his fleet. The Lion and Luther engaged in single combat. In this battle Lion El'Jonson wounded Luther but could not bring himself to kill his oldest and dearest friend. Luther, however, was merciless and sent a sorcerous blast straight towards Lion El'Jonson which mortally wounded the Primarch. At that moment, realizing how far he had fallen, Luther began to weep for what he had done to his friend, and the Dark Angels captured him and held him prisoner on [[the Rock]]. At this point, the Gods of [[Chaos]] scattered Luther's forces, the [[Fallen]], through the [[warp]]. The intense battle, however, had made the planet unstable, and Caliban was destroyed{{Cite This}}.