The Anathame was a sword impregnated with the power of the Chaos God Nurgle created by the mysterious Kinebrach, a species of simian-like humanoid aliens who co-existed with the humans of the Interex culture in the years before the start of the Great Crusade in the late 30th Millennium. If the name of a target was spoken to the blade, the weapon would become totally inimical to that being on an almost molecular level, producing poisons and toxins tailored specifically to them, while also guiding itself towards its target.
This blade was stolen by the Word Bearers' Chaos-corrupted First Chaplain, Erebus, from the Hall of Devices in the Interex's Museum of Technology on Xenobia. Xenobia was the Interex world that the Imperium's 63rd Expeditionary Fleet commanded by the Warmaster Horus was visiting in a failed diplomatic attempt to open peaceful relations between the Interex and the Imperium of Man. The Kinebrach Anathame was then used through a series of events largely orchestrated by Erebus to mortally injure Horus while he was in combat against the Forces of Chaos on the Plague Moon of the Feral World of Davin, ultimately forcing him to seek a cure in the Temple of the Serpent Lodge on Davin.
At the temple he was corrupted to the service of the Dark Gods by his own mad ambition, and became determined to overthrow the Emperor of Mankind. Later, Erebus would strike eight shards from the blade of the Anathame just before the Battle of Calth to create the Chaotic daggers known as the Athame that were used by the Word Bearers Host of Chaos Space Marines that assaulted that world during the Horus Heresy.
The mysterious xenos known as the Kinebrach were a species of simian-like humanoid aliens who co-existed with the humans of the advanced Interex civilisation for many centuries before the Great Crusade reached their area of the galaxy in the early 31st Millennium. Long before humanity had spread across the stars from their homeworld of Terra, the Kinebrach ruled a large and mighty interstellar empire. However, by the time the humans of the Interex made first contact with them, the Kinebrach empire was old and decaying. The Kinebrach were particularly notable for the sophistication of their weapons, which were quite advanced when compared to that of the Imperium at its height in the early 31st Millennium, though their military technology lagged somewhat behind.
The Kinebrach, rather than go to war against a more vibrant and powerful species, decided to ally themselves with humanity instead. Thus, the Kinebrach were taken under the wing of the Interex, with certain limitations placed upon them. The foremost of these was that no Kinebrach was allowed to carry arms, except in times of war. Those Kinebrach in the Interex military served as shock troops due to their strong, stocky build. The Interex's technology, at the time of that civilisation's first contact with the Imperium of Man, was very advanced, in some ways more so than than that of the Imperium at its height, and was one of the reasons the Interex was able to progress so quickly as a culture.
Architect of Fate
First Chaplain Erebus and the rest of his Word Bearers Space Marine Legion was secretly in league with the Ruinous Powers of Chaos since they had been humiliated by the Emperor for their violations of the Imperial Truth on the world of Khur over 40 standard years before the start of the Horus Heresy. Erebus became a very close confidante and adviser of the Imperial Warmaster Horus. The Words Bearers, who originally had worshipped the Emperor as a God and whose Primarch Lorgar had penned the Lectitio Divinitatus before he turned against his father following the events on Khur, had been brutally reprimanded for their constant erection of temples and shrines dedicated to the worship of the God-Emperor on newly conquered worlds. This was a policy that had directly violated the Emperor's secularist philosophy and had slowed the XVIIth Legion's progress in the Great Crusade to a crawl. In the wake of his humiliation and the reprimand against his Legion on Khur, Lorgar had sought to discover whether there truly were divinities worthy of human worship during the quest that came to be known as the Pilgrimage of Lorgar.
During this journey, Lorgar entered the Eye of Terror and came face-to-face with the "truth" of the Primordial Annihilator, the force later called Chaos by Mankind that he believed was truly divine and worthy of his service and the worship of all humanity. He brought this faith to his Legion, and soon all the Astartes of the Word Bearers believed that the Chaos Gods were more worthy of their loyalty and worship than the Emperor who had proved himself to be a false god. With the guidance of the Ruinous Powers, Lorgar and the Word Bearers hatched their secret plans over the course of the next four decades to convert humanity to the service of the Ruinous Powers, starting with Horus. After Lorgar placed his agent near Horus, Erebus slowly managed to twist the thinking of Horus against the Emperor and turn half of the Mournival, the Warmaster's most trusted advisers within the XVIth Legion, towards the same path of treachery by exploiting their intense loyalty to their Primarch over that for their far more distant Emperor.
The Interex Compliance
The world of Xenobia was first encountered by the 63rd Expeditionary Fleet of the Luna Wolves Legion, under the command of Horus during the latter days of the Great Crusade in the early 31st Millennium. The Interex were aware of the existence of Chaos (referred by them as "Kaos") and were devoted to fighting its corruption. As a result, the Interex was highly suspicious of the Imperium's intentions, as they believed that the interlopers from Terra might be servants of the Ruinous Powers. While Horus and his Mournival were treating with the leaders of the Interex, First Chaplain Erebus of the Word Bearers, who had been accompanying the Warmaster as part of his entourage and who was already a secret follower of the Chaos Gods, infiltrated the Hall of Devices on Xenobia, a museum that contained various artefacts and weapons drawn from the history of the Interex and their allied alien species.
His objective was to steal the highly valuable and deadly Kinebrach blade known as the Anathame, a Chaotic artefact sacred to the Plague God Nurgle. After claiming the blade, Erebus rigged the building to explode to make good his escape. Feeling betrayed by the Imperials, who they took for agents of Chaos for stealing a known Chaotic artefact, the Interex's troops immediately attacked the bewildered forces of Horus, sparking a deadly confrontation. The Warmaster was evacuated off-planet by his Astartes as the Luna Wolves unleashed their full might upon the Interex. The Anathame would later play a pivotal role in the corruption of Horus by the Dark Gods upon the Plague Moon of Davin. The Interex were later destroyed by an Imperial military campaign and all of their worlds were brought into Imperial Compliance.
Corruption of Horus
The Word Bearers' plot reached its climax on the Plague Moon of the Feral World of Davin, where Horus was wounded during a struggle against Eugen Temba, the former Imperial Planetary Governor of Davin who had rebelled against the Imperium following his corruption by Chaos. The Anathame that had been stolen by Erebus from the museum of the Interex had been given by the corrupted Chaplian to Temba. Temba had been corrupted by the powers of the Warp and had become a mutated servant of Nurgle, the Chaos God of disease and decay. During a confrontation on the Plague Moon in the ruined remains of Temba's Imperial warship that was orchestrated by the Word Bearers' First Chaplain, the corrupted Temba managed to seriously wound Horus with the malefic blade by stabbing the Primarch through his left shoulder. When the Luna Wolves found the wounded Primarch, the Mournival moved the Warmaster to the Medicae aboard the XVIth Legion's flagship, the Vengeful Spirit.
The Apothecaries of the XVIth Legion proved incapable of healing the Warmaster's wounds despite every form of advanced medical technology at their disposal, until it seemed that Horus would surely die. The Luna Wolves' notable Apothecary Vaddon examined the Primarch's wound, discovering that the fell weapon's toxins rendered even Horus' superhuman immune system powerless in the fight against them. His Larraman Cells were no longer functioning correctly, and so the open wound could not clot properly, causing Horus to bleed profusely. Vaddon informed Captain Garviel Loken of his findings, explaining that in order to save the Warmaster, he needed to examine the weapon that had wounded him. Captains Loken, Tarik Torgaddon, Sergeant Nero Vipus and members of the Luna Wolves' Locasta Squad went back down to the surface of Davin's moon to retrieve the Anathame.
Erebus then convinced the Luna Wolves' warrior lodge to allow him to take Horus to a secret sect on Davin and use the sorcery practiced by the Temple of the Serpent Lodge to treat the Warmaster. The creation of a warrior lodge within the Luna Wolves and many other Space Marine Legions over the course of several decades based on the lodges used by the savage warriors of Davin had been another of the Word Bearers' ploys to infiltrate and corrupt the Astartes into turning against the Emperor. Following the "miraculous" recovery of Horus on Davin after he turned to the service of Chaos and dedicated himself to overthrowing the Emperor in return for his resurrection, the Anathame was mysteriously taken away from Apothecary Vaddon by the Emperor's Children Chief Apothecary Fabius. Fabius bore the Warmaster's Seal, which enabled him unlimited access to any artefacts he required. Fabius then delivered the weapon to his Primarch Fulgrim, which Horus had arranged as a gesture of trust. Shortly before the Istvaan III Atrocity, Fulgrim used the Anathame to kill Lord Commander Vespasian.
He later used it to kill Remembrancer Ostian Delafour in his studio aboard the IIIrd Legion's flagship, the Pride of the Emperor, impaling him through a painstakingly-sculpted statue of the Emperor of Mankind that offended Fulgrim's new Chaos-tainted sensibilities. Fulgrim left Ostian and the Anathame, where Serena D'Angelus would later kill herself on the protruding blade. Fulgrim later reclaimed the blade, but he allowed Erebus, the First Chaplain of the Word Bearers Legion, to strike eight shards from the Anathame just before the Battle of Calth and fashion them into the Chaos-tainted daggers known as Athame. He gave seven of the Athame to the commanders of the Word Bearers Host deployed to Calth, including Kor Phaeron, Morpal Cxir, Foedrall Fell, Hol Beloth, Quor Vondar, Phael Rabor, and Kolos Undi. Erebus also gifted an Athame to Criol Fowst, a human leader of the Chaos Cult known as the Brotherhood of the Knife that was in service to the Word Bearers at Calth. Fowst used his Athame to sacrifice victims as part of the Word Bearers' summoning ritual during the Battle of Calth. He considered it his most treasured possession, and was enraged when he lost it to Oll Persson. Persson later used this Athame to cut a rift in realspace which allowed him and a small group of survivors to escape the poisoning of Calth's atmosphere.
The Anathame eventually returned to the possession of the Emperor's Children Chief Apothecary Fabius and he learned how to influence its daemonic sentience. When Felix Cassander broke free of his restraints and attacked him in his vivisectorium, Fabius took the Anathame and named Cassander to it, and then struck a glancing blow to Cassander's shoulder. Instead of dying, Cassander was wracked with pain beyond that which even Fabius had ever inflicted upon him.
Fulgrim ultimately brought the Anathame with him to Iydris, a Crone World at the heart of the Eye of Terror, and used it to ascend to daemonhood in accordance with the Eldar prophecy regarding the forbidden weapon known as the Angel Exterminatus.