The Baksuryan Orders was the name given to a group of Chaos Cults first found to dominate the city of Thelmpacia on an unknown world during the Great Crusade. The cults' origins were believed to stretch back to pre-Unification Terra to the sub-Indus archipelagos, where the Emperor of Mankind had first encountered the Order of Baksurya the Hungerer.
These beliefs had continued to exist in one form or another even after the Unification Wars, and were eventually transmitted across the galaxy in hidden form by the Imperial armies of the Great Crusade.
Elucidators of the Office of the Sigillite in the process of purging the city of Thelmpacia of a group of cannibals and Warp-worshippers recovered an unexpected item in their possession: the intact helmet of a Thousand Sons Legionary. Concealed within its lining was a scrawled parchment, assumed to have been written by its erstwhile owner, recalling in summary the findings of an investigation into the organisation. According to the handwritten notes, which remain uncorroborated due to the thorough ounitive efforts of the Elucidators, Thelmpacia had fallen under the thrall of an ancient faith.
Calling themselves the Devourers, the members of this group worshipped an entity called Haksujan, a "holy being" renowned for its insatiable appetites. Haksujan, according to local myths, judged its servants by their martial strength, its worshippers meeting in secret to undertake ritual melees.
The leaders of the Order were the most accomplished pugilists in these brawls, their might and martial prowess being their criteria of selection, and their strength only appeared to grow with the favour of their brethren and their deity. If the combat resulted in a death, as it should per the tradition of the Order, all of the fighters present would partake in eating the corpse of the fallen, emulating the appetites of their divine master.
Parallels were drawn on the recovered parchment between the behaviour of the Devourers and dozens of other incidents of occult activities throughout the galaxy, tracing back to pre-Unification Terra. Apparently well-versed in the occult, the author of the note linked the ritual practices of the Devourers with the Brotherhood of Godann on Beta Hethacon, and with the Chidlren of Jumnuka on Rothberg VI. The author went on to theorise that all such organisations descend from that of the Order of Baksurya the Hungerer, a faction encountered by the Emperor on the sub-Indus archipelagos of Ancient Terra.
Though ostensibly eliminated by the forces of the Unification Wars, their beliefs remained subtly present in the Emperor's domains and were ultimately carried across the stars during the Great Crusade by His armies. This is substantiated, claims the scrawled text, by the fact that all worlds touched by the outbreak of similar groups were brought to Imperial Compliance by the 73rd Expeditionary Fleet, which carried warriors from that region of Terra.
Though purged one by one, similar groups appeared in other areas of the galaxy and were thought to have been propagated by soldiers of the Great Crusade, who in the field may have witnessed and them imitated their saviours amongst certain Legions of the Space Marines partaking in a limited form of anthropophagy allowed by their gene-seed implants.
When eventually returned to the XV Legion, the helmet was identified as that of Mykolayiv Bast, Fated Vigilator of the Thousand Sons Ammitara Occult, who was declared missing in 890.M30. Bast's helmet was repowered by the armourers of his Legion and extensive audio dictation was discovered in its data-core, detailing the findings of his investigation into the Haksujan Order and presumably other such related groups.
The Thousand Sons deemed this report to be too dangerously arcane to share with the officers of the Sigillite and accordingly claimed to have destroyed the helmet and its contents. Though multiple petitions were filed, the XV Legion would not explain the reason behind Bast's concealed presence in Thelmpacia, or the full extent of his investigations into the matter.
- The Horus Heresy Volume Eight - Malevolence (Forge World Series), by Neil Wylie and Anuj Malhotra, pg. 18