With the secret gene-seed tech, Corax attempted to boost the numbers of his Legion. The Alpha Legion had other plans unfortunately.
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Upon escaping the tailing forces of World Eater’s picket ships, “Avenger” broke real-space into the warp, and headed for Terra. Upon arriving Corax headed for the Imperial Palace, which was being fortified by Rogal Dorn and his Imperial Fists in preparation for the coming Siege (Siege of Terra), upon which after much argument with Dorn and Malcador the Imperial Regent, The Emperor himself boomed in a psychic voice for the arguing to cease and pulled Corax into a vision of extreme light, and showed him the secrets he had been asking for – The gene forging tech used to create the Primarch’s by the Emperor himself. After navigating the treacherous and dangerous contraption which was the ever shape-shifting maze on Luna, by using his advanced logic, and the skill of his sons to out-think its logic engine and freeze it in place, he retrieved the gene tech and returned to Deliverance under the watchful eye of the Adeptus Custodes (who were charged by Malcador to keep an eye on its safety).
At first the Astartes created by the gene tech were a marvel, a splice of Primarch and Astartes, but not in an imbalanced degree so as to cause malfunction, a perfect meld. These new warriors were faster, stronger, and more intelligent than any of the older warriors of the Legion, and within a few weeks more aspirants had been successfully implanted with stable gene-seed than ever before (the new gene seed also meant that warriors matured into their new forms rapidly compared to standard Astartes). The new warriors would be placed under the command of Captain Branne Nev under the moniker “Raptors”, and would be used against a Word Bearer fortress as their first deployment, which would see them successfully slaughter veteran Word Bearers with the ease of much older warriors. Raptors would take injuries that would have killed even an Astartes, and still remain fighting due to their enhanced bodies. Word of this reached the ears of Omegon, twin Primarchs of the Alpha Legion, whom had been laying dormant on Kiavahr below stirring up a rebellion amongst the tech guilds, and he sprung into action.
The rebellion and even the Alpha Legionnaires supporting it were a distraction, while the Raven Guard were caught off guard, Omegon and several Alpha Legion operatives managed to covertly spike the gene tech with a daemon blood poison (while managing to keep the pure technology for themselves) using the Raven Guard gene-seed to produce deformed monsters. The battle finally began as the first Raven Guard recruits to receive the secretly spiked gene seed were implanted, and by the time it raged into the gene labs of Ravendelve, only to be met by deformed warriors created by the spiked gene seed’s effects.
While deformed, these Astartes still fought with otherworldly strength, overpowering even the Alpha Legion Astartes. By the time the battle was over, Agents had been found amidst the legion, explaining how news reached the traitors about the gene tech, and thus the loss of such a boon to the crippled legion, gene screening was to be implemented to find and destroy the agents with the stolen faces of Raven Guard Legionnaires. Corax nevertheless led the Raven Guard in full strength (~4000 Astartes) and his allies (over 500,000 Therion Cohort, 100-150 Imperial Fists, 20 Custodes against The Perfect Fortress, an Emperors Children stronghold.
Planned to be conducted with his legion rebuild to be at least 10.000 Astartes strong, the Fortress was taken by luring the Traitor forces out with an failed assault by the Therion Cohort. While Raven Guard losses were small, the Traitor force was totally destroyed. The Perfect Fortress was on a important strategic planet for the whole sector, but Corax withdrew his legion to strike the next Traitor force, leaving the garrison to the Therion Cohort, and the expected Imperial Army and Titan Legion Reinforcements. Corax again led the Raven Guard in full strength against traitor forces in the Battle of Yarant, rescuing the Space Wolves. After the battle, Corax expressed his intent to continue to resist Horus from the shadows.
Without the gene tech the Raven Guard Legion remained a small legion, though their continued work with small cells of warriors allowed them to remain no less of a fighting force, though fewer in number then before. Tales of the Space Wolves report the use of Astartes more beasts than man (from the raven guard side). The Space Wolves never reported this to any imperial authorities, most likely because they shared a sympathy with the Raven Guard because of their own similar flaw.
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