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"These Knights are vital components of the Taghmata that protect Forge and Fane, yet despite their pride, they are but one tool among many and they will bend to the Omnissiah's will or be broken by it."

— Noted comments of Archmagos Draykavac upon the rediscovery of House Atrax, ca. 3447.853.M30

House Atrax was a House of Renegade Knights that was forced to repudiate its oaths to the Emperor of Mankind and followed the Warmaster Horus into the service of the Ruinous Powers during the Horus Heresy. Founded sometime during the Age of Strife and rediscovered during the Great Crusade by the dour Mechanicum Tech-adepts of the Forge World of Cyclothrathe in the late 30th Millennium, this unfortunate Knight House was forced into indentured servitude in accordance with the Sidon Protocols.

The complex web of obligation and duty that was enshrined in the Sidon Protocols bound both House and Forge World in a dangerous accord, whose tangled precepts often times easily led to the loss of any semblance of independence for a Knight House that failed to uphold the protocols. These unfortunate circumstances were what led to House Atrax's tragic fall to Chaos during the Horus Heresy.


Questoris Knight Styrix House Atrax

House Atrax Questoris Knight Styrix Colour Scheme

Those Knight Houses that remained in contact with one of the far-flung Forge Worlds of the Martian Cult Mechanicus during the Age of Strife have most often fallen into a symbiotic relationship with their patron, receiving technological and spiritual guidance from the Magi, while themselves acting as a potent shield for the Forge World. Many Forge Worlds might have faded from history during the Age of Strife were it not for the tireless efforts of the Knight Houses bound to their service. Such a joining of the cold logic of the Mechanicum and the impassioned zeal of the more typical Knight Houses led to many widely-varying oaths. Most common among these oaths was the form that had come to be known as the Sidon Protocols. Among the more well-known rights provided by the Sidon Protocols was that of the Knight House to bear the symbol of the Opus Machina, the Mechanicum's sacred cog wheel-set skull, as part of their panoply of arms. This was both a sign that they carried with them the authority of Mars and the Cult Mechanicus, as well as a mark of their duty as part of the Taghmata of their patron Forge World.

Only a few Houses maintained contact with the domains of the Mechanicum throughout the Age of Strife. Undoubtedly many of those that did not have long since perished, overwhelmed by the terrors of Old Night, or have lost the last of the Knight armours that marked them out, devolving into simple Feral Worlds that maintained only the neo-feudal traditions of their origins. Those few that survived the trials of the Age of Strife, prevailing alone and unaided, were much sought-after prizes for the expanding armies of Mankind. The Expeditionary Fleets of the Great Crusade went to great lengths to secure such a world, prizing the skill of a House's warriors and the power of their Knight armour. However, it had long been the Imperium's policy to secure the loyalty of these rediscovered Houses directly to the Emperor of Mankind and for Imperial factorums to represent the House in all dealings with the Mechanicum.

Yet, despite the efforts of the Emperor's servants, some few Knight Houses escaped the Emperor's servants, only to be chanced upon by Mechanicum Explorator vessels alone or ceded to the control of a Forge World in exchange for some portion of its industrial output or the services of its assembled Taghmata. Such rediscovered Knight Worlds, often sorely in need of new armours and lacking any long association with their new patron Forge, found themselves caught in something of a devil's bargain. Their dire need for technological expertise and replacement armours served as a simple leash for the coldly logical Archmagi to wield in order to seal the Knight House to their service, and one that was applied with chilling efficiency. Where in some cases the Sidon Protocols served to bind together House and Forge World in amicable alliance, in the instance of House Atrax and the Cyclothrathe Mechanicum, the complex terms of debt and duty were manipulated to strangle the independence of the House.

Bound in servitude to the grim Forge World of Cyclothrahte, the once-proud warriors of the House of Atrax suffered much since Archmagos Draykavac blasted their homeworld into submission. The House of Atrax survived all the horrors of Old Night through stubborn force of arms, but over two solar decades under the direct control of Draykavac had left them a hollow and distorted reflection of their former glory. Systematic and bloody purges of those scions who displayed any hint of rebellion had left the scions of Atrax a grim and brooding people in whom their Mechanicum overlords had fostered a disturbing hatred of those who had escaped the fate that had befallen them.

The poisoned husk of House Atrax's homeworld, Arrian, served the Magi of Cyclothrathe as a source of raw materials for their wars of conquest and expansion, with legions of imported slaves tearing the ore from the blackened rocks. The remaining scions of Atrax were confined to the armoured vaults that lay beneath Arrian's scorched surface, released from this virtual captivity only when Draykavac summoned them to war. The Knight armours of the House were kept separate from the scions, ministered to by Cyclothrathe-trained Sacristans as hostages for the scions' loyalty, for in the case of any armed revolt, the Archmagi of Cyclothrathe could destroy all of the House's Thrones Mechanicum with but a word.

With Cyclothrathe pledged in tacit supports of Horus' treacherous campaigns in the northern reaches of the sundered Imperium, Draykavac unleashed the warriors of Atrax on the worlds of the Coronid Reach. There, the twisted scions took a measure of revenge by slaughtering those who had not suffered over the years as they had, exulting in the freedom to stalk the surface in their armour before Cyclothrathe caged them once again. The House's final fate remains unknown in Imperial records.


Coronid Reach

Ancient Departmento Cartographic stellar map of the Coronid Reach

Arrian was a sulphurous, poisoned world with an atmosphere thick with chlorine gas, and therefore utterly inimical to human life. Rich in minerals and easily accessible chemical deposits, large-scale mining and extraction facilities had been rapidly constructed across the world's surface to meet the industrial needs of Cyclothrathe, of which Arrian was a directly-administered possession.

Lacking a native population, Arrian's miners were directly imported by the Magi of Cyclothrathe, their hellish existence made only possible by extensive augmetic adaptation, despite which mortality rates were disastrously high. For many Terran years, the demand for new labour was met by treaty arrangement between Cyclothrathe and the distant worlds of the Manachean Commonwealth, trading convicts by the thousand in return for arms and other advanced products of Cyclothrathe's forges. During the onset of the Horus Heresy, however, with Cyclothrathe's growing isolation, this agreement had been allowed to lapse and how the presumed shortfall in labour was replaced remains unknown.

Notable Campaigns[]

  • The Liberation of Numinal (ca. 009.M31) - The Knights of House Atrax had long been used as a personal bodyguard for their master, the baleful Archmagos Yelav Draykavac who had ordered them to protect the amphibious crawlers that would reprocess Numinal's civilian population into Adsecularis slaves and mindless Servitors. With the planet's counter-invasion by Loyalist Solar Auxilia troops known as the Agathean Cohorts, the Knights of House Atrax assembled to crush the invaders after their first attack failed. As the Knights were about to engage the enemy, Ireton MaSade, commander-in-chief of the Agathean Cohorts, deployed his own Knights at the host's rear flanks, via a daring Drop Pod assault. Trapped between these newly arrived foes and the disciplined ranks of the Solar Auxilia, House Atrax moved to protect their master, who did not hesitate to sacrifice each and every one of them to deliver himself to safety. Abandoned, overwhelmed by their enemies, and outclassed by the more agile Cerastus Pattern Knight armours of House Orhlacc, House Atrax suffered a crushing defeat.
  • Battle of Beta-Garmon, "The Titandeath" (006-013.M31) - House Atrax took part in the long and savage Beta-Garmon campaign, which included hundreds of war zones across dozens of worlds. During this conflict, House Atrax provided Knight support to the Legio Magna. Even before the greater armies of the Warmaster Horus reached the star cluster, the battle lines had long since been drawn, and fighting had been going on for many Terran years. It was a cauldron of battle that would consume millions of lives before its end and see the demise of entire Titan Legions, earning this campaign the dire moniker of "The Titandeath." The Beta-Garmon Cluster, also known as the gateway to the throneworld of Terra, was the last hurdle that the Warmaster Horus' forces had to overcome before they reached the Imperium's capital world. Heavily fortified by the Loyalists, Beta-Garmon would become one of the greatest and bloodiest battles of the Horus Heresy, as well as one of the longest-lasting.

Notable House Atrax Knights[]

  • Rhadamanth - Rhadamanth was a Questoris Knight Styrix piloted by Atrax scion Andar Thon during the Horus Heresy era. This infamous Knight was released from its confinement on Arrian to the control of Scion Thon for the assault on the Agri-world of Numinal. Rhadamanth, whose Throne Mechanicum was tainted with aberrant malefic-Machine Spirits, claimed four confirmed Knight kills during the fighting, despite the bleak fury of Scion Thorn and the other Atrax warriors, for whom defeat and death in battle held perhaps little terror when compared to servitude to Cyclothrathe. Rhadamanth was eventually surrounded and destroyed during the retreat of Draykavac's forces, Scion Thon battling on even as his armour was torn apart by Loyalist Knights and robotic Battle-Automata.

Notable House Atrax Personnel[]

  • Andar Thon - One of the scions of House Atrax, Scion Thon piloted the Questoris Knight Styrix known as Rhadamanth. He died during the campaign on Numinal.

House Appearance[]

House Atrax Banner

Personal heraldry of Andar Thon, which consists of the House symbol, its colours inverted, adorned with triple lightning bolts and with the emblem of Cyclothrathe placed surmounting the personal arms of the scion

House Colours[]

With such strong connections to the Forge World of Cyclothrathe, House Atrax bore black and the red of the Mechanicum as its livery.

House Arms[]

The arms of House Atrax were three white daggers on a field of crimson, with the symbol of the Forge World of Cyclothrathe centered above it; the blood-red sigil of that dread Forge World more a mark of ownership than a symbol of alliance. Typically, many Knight armours operated by House Atrax lacked adornment and personal icons; the dour Tech-adepts of Cyclothrathe saw little military use in such extravagance and had forbidden the Thrall-Knights of Atrax its use. The Thrall-Knights' upper dorsal plating would often bear the mark of the Sidon Protocols, though House Atrax suffered under a particularly harsh interpretation of this pact. On the Thrall-Knights' personal banners, the emblem of Cyclothrathe was placed surmounting the personal arms of the scions to indicate the primacy of Forge over House.


  • The Horus Heresy - Book Four: Conquest *Forge World Series) by Alan Bligh, pp. 76, 98, 102-103
  • Adeptus Titanicus - The Horus Heresy: Titandeath (Specialty Game), pg. 95