Ordo Reductor Icon

Icon of the Ordo Reductor

The Ordo Reductor is a specialised military division of the Adeptus Mechanicus that makes use of the forbidden weapons of a bygone age, engaging primarily in siege warfare. Known to their fellow adherents in the Machine Cult as the "Bringers of Blessed Ruin", the Ordo Reductor's sacred role is that of the un-maker, slaughterer and breaker; they embody the animus of the Omnissiah, its duality not as a creator or embodiment of knowledge, but as destroyer and bringer of oblivion. The Ordo Reductor was particularly active during the Great Crusade and the Horus Heresy, and deployed the potent cybernetic shock-troops of the Mechanicum known as the Thallax. They have a different interpretation of the Cult Mechanicus than their peers among the Tech-priests, seeing the Machine God and the Omnissiah as the divine embodiments of destruction itself, naming Him the Unmaker God.


The Ordo Reductor were known for being preeminent siege specialists, destroyers and world breakers, having access to many archeotech devices and forbidden technology. Their given title, whose prefix was unusual for the servants of the Mechanicum, was invoked first by the great treaty between the Lords of Mars and the Emperor of Mankind, although their true and forgotten origins delve back into the dust and blood of the Age of Strife on the red world of their birth. By this order, a sub-clause of the very compact by which the alliance between the Mechanicum and Terra was sealed, was the Ordo Reductor created for the express purpose of sundering and destroying those who would stand against the Great Crusade. Where a new and terrible alien form of life was encountered that would not succumb to the Imperium's panoply of war, it would be the biologis of the Ordo Reductor who would find a way to kill it; where a recalcitrant human techno-empire stood strong against the Great Crusade fleets, it would be the preceptors of the Ordo Reductor who observed and analysed their weapons and defences to find their weakness. Most famously, where a fortress stood seemingly impregnable, it would be the Ordo Reductor who would find a way to bring it low.

The Ordo Reductor's numbers, however were always relatively few, accounting only for a handful of the most bellicose of the Magi of Mars in the beginning, split from their forges and domains henceforth to serve the Great Crusade first and their feudal masters of the Mechanicum second in all things. Even as other Forge Worlds were contacted and brought into the Imperial fold, their numbers did not increase greatly and it is often said, and not without evidence, that those Tech-priests and Magi given up to the Ordo Reductor by their birth worlds or who were drawn to it of their own volition were often already seen as outcasts; either dangerously heretical in their leanings or overly-independent and perhaps psychologically unstable by their peers. However, within the fold of the Ordo Reductor were such individuals redeemed in the doctrine of the Cult of the Omnissiah and given righteous purpose in the service of the Mechanicum -- as well as removed largely from the feudal politics of the Forge Worlds. And so while they became "other" to those who remained directly under the shadow of Mars, they were not considered with the same levels of suspicion and distrust as followed that parallel Mechanicum faction which also shared the battlefields of the Great Crusade with them, the Legio Cybernetica.

The Covenants of War

The individual commands of Ordo Reductor Magi and their attendant servants and war machines, known commonly as "Covenants", were based almost entirely on purpose-configured warships. These were often long-range, self-sustaining Galleass types birthed in the vast shipyards of Saturn for this express task, rather than the more common Arks-Mechanicum. It was these voidships which served as transport, fane and permanent base for the Ordo Reductor in the days of the Great Crusade and were their only sovereign domains, but domains they guarded jealously, even from their brother Mechanicum. The very treaty that had created them had also split the Ordo Reductor from the Forge Worlds and the bulk of the Mechanicum in a very real sense, and set them in thrall on the front lines of the Great Crusade from where they would seldom stray. The "Brazen Vultures" of the Ordo Reductor, as the void captains of the Imperialis Armada came to call their ships, passed as baleful mendicants and nomads from war zone to war zone as the ebb and flow of the fighting -- or the will of some Primarch or other great lord of the burgeoning Imperium -- dictated.

Because of their relatively small number, wide physical dispersal and their calling as war-savants, more often than not Ordo Reductor Covenants served the various Expeditionary Fleets and theatre commands in the roles of battlefield intelligence gatherers, warrior-seers and savants of carnage rather than as conquerors in their own right -- the Space Marine Legions more often than not putting into practise what an Ordo Reductor Magos' blood-drenched wisdom had learned to deadly effect. The Reductor's own forces were seldom seen to act directly in battle save to conduct targetted raids and probing strikes ahead of a main advance, or to haunt still-burning battlefields making a tally of the dead and the destroyed to further their studies. This disposition held true in most cases except one; that of siegecraft. This sphere of warfare with all of its lethal complexities and unforgiving logic was to the Magi of the Ordo Reductor a thing of sublime and dark mystery, and in its discipline they found purity and in its merciless execution they found the echo of the divine Omnissiah. In the arts of the siege, the Magi of the Ordo Reductor acknowledged no superior and few equals in their cold pride, save a handful of the Primarchs of the Legiones Astartes. This presumption was not without its justification, as in countless sieges and assaults, the Covenants of the Ordo Reductor proved able to sunder defences thought unconquerable and survive Zone Mortalis battles located where no human and perhaps no Astartes could have fought and lived.

In structure, the Covenants of the Ordo Reductor fought and operated as autonomous war bands, self-sufficient in almost all respects, containing a mixture of Magos and Tech-priest savants whose specialities ranged from tactical assault to macro-firepower to mimetic and forensic battlefield analysis to munitions production. Its weapons were many and deadly beyond reason, for to the Ordo Reductor was the right given to bear arms forbidden since the Dark Age of Technology and arcana deemed too unpredictable and dangerous for general deployment by the Great Crusade. Also, theirs by Dictate Imperial was the right -- within certain parameters -- to innovate new weapons and war machines in order to overcome the countless enemies the Great Crusade faced. This license bore fruit in many ways during the countless wars which made up the Great Crusade, from the development in concert with the Imperial Fists Legion of the peerlessly durable Land Raider Achilles, to the development of the powerful Eradication Cannon mounted on the Hellion-Minoris war machines of the Centurio Ordinatus, devised expressly for the Rangdan Campaign.

Perahps the most widespread of the Ordo Reductor's creations is however the Thallaxii; heavily augmented cybernetic shock troops created by the Ordo Reductor to replace the Skitarii legions of Mars, to which, owing to their own separated status, they no longer had direct or ready access to for support. As well as serving first and foremost as the Ordo Reductor's soldiers of the line, the extremely potent and durable Thallax were also gifted or traded by the Ordo Reductor Magi to other factions of the Mechanicum as the Great Crusade went on, most notably to the Taghmata of Forge Worlds and outposts that were far separated from Mars, as well as elements of the Legio Cybernetica and the Myrmidon sub-cult (which often found common doctrinal cause with the Ordo Reductor) in return for reciprocal agreements of supply and allegiance. This served to both greatly increase the power and independence of the Ordo Reductor and, it has been argued by some, also contributed to the waning of Mars' direct military control over its outlying Forge Worlds in the solar decades before the Horus Heresy.

The Hidden Order

As diffuse a military organisation as the Ordo Reductor was during the Great Crusade, and as unfathomable as its inner workings were to outsiders, it nevertheless showed a long history of successful tactical and strategic integration with the forces of the Great Crusade alongside which it served. This was evidenced not least of all by the willing incorporation of the heraldry and livery of the Space Marine Legions with which a particular Covenant (or more rarely a demi-Legio comprised of several Covenants) had been embedded for an extended period, and honours from such campaigns were retained in pride of place in the livery of their war machines and Servitors. It was for this reason, much as with other detached Mechanicum military formations such as the Titan Legions, that when the Horus Heresy erupted across the galaxy and split the forces of the Imperium, so was the Ordo Reductor also split, with its bellicose sigil of the broken tower present among the banners of Loyalist and Traitor alike.

It is however true in the final analysis that a discernible percentage of the Ordo Reductor ultimately sided with the Loyalists' cause over that of the Warmaster Horus, and a very few took the same path as other certain outlying Forge Worlds and chose to withdraw support from either side of the conflict, declaring independence. It is not known why in this the Ordo Reductor should be so singularly different to the Titan Legions or the Martian Mechanicum, who on reflection favoured to a margin the Traitors' cause, or the various Taghmata, swayed by the rulers of their Forge Worlds going where they led. But it may simply be that the majority chose to ultimately honour the deeds and purposes of their genesis over more temporal concerns, or as some have less favourably theorised, that in opposing the forces of the Warmaster and his treachery, many saw the greatest challenge to their arts of war.

Notable Campaigns

  • Istvaan III Atrocity (ca. 006.M31) - Units of the Ordo Reductor under Magos Calleb Decima were among the few Loyalist survivors of the Istvaan III Atrocity that marked the beginning of the Horus Heresy.
  • Drop Site Massacre (ca. 006.M31) - Units of the Ordo Reductor supported the first wave of Loyalist Space Marine Legions during the infamous Drop Site Massacre on Istvaan V. The assault on Istvaan V went badly for the first wave, comprised of the Iron Hands, Raven Guard and Salamanders Legions, when the second wave of Legiones Astartes revealed themselves to be sympathetic to the cause of the Warmaster Horus. These three Loyalist Legions and their supporting units were all but wiped out in the subsequent fighting, marking one of the darkest days in the Imperium's history.
  • Achilus Crusade (ca. 777.M41) - At the outset of the Achilus Crusade to reclaim the Jericho Reach located in the outer reaches of the Segmentum Ultima for the Imperium, the Ordo Reductor sent two Siege Formations as a part of the supporting contingents supplied by the Adeptus Mechanicus for the Crusade.
  • 13th Black Crusade (999.M41) - When Abaddon the Despoiler and his Forces of Chaos assaulted the Fortress World of Cadia during the 13th Black Crusade in 999.M41, the Ordo Reductor aided in the defence of that beleaguered Imperial Fortress World by providing a Demi-legion of their coveted war engines.

Forces of the Ordo Reductor

  • Mechanicum Thallax Cohort (pl. Thallaxii) - During the Great Crusade and Horus Heresy eras in the late 30th and early 31st Millennia, the Ordo Reductor possessed a faction of heavily augmented cyborg shock-troops called the Thallax Cohort. The Thallaxii differed from the standard Skitarii regiments both in their purpose and the unique degree of their augmetics. The Thallaxi Centuries utilised a divergent form of Power Armour technology known as the Lorica Thallax, which, unlike that used by its Space Marine counterparts, was permanently, surgically-bonded to the body of the wearer. The Lorica encloses the major organs, nervous system and cerebrum, but entirely replaces the skeletal structure and limbs with armoured bionics powered by an internal reactor-core. Surgical excision of the subject's pain sensors, emotions, and normal human sensory apparatus and the agony caused by the Lorica 's implantation, leaves the Thallax a cold, calculating killing machine (albeit one that retains a degree of independent thought). To some amongst the Mechanicum, this operation skirted the edge of abomination, yet the baleful Ordo Reductor continued Thallax conversion regardless; using suitable Forge Guard, fallen Skitarii, and other subjects obtained from more mysterious sources. It is not known if the Ordo Reductor still possesses the archaic technology used to create Thallaxii troops in the present era of the late 41st Millennium.
  • Mechanicum Ursarax Cohort (Ursaraxii) - A development of the later Great Crusade, the Ursarax Tech-guards were first designed by the Explorator Magos Enabrin Falkan as a heavy, rapid-moving close combat unit for use by the notoriously independent Magos' forces. Using a fusion of existing technologies sacred to the Mechanicum, materials and patterns taken from the Thallax of the Ordo Reductor (much to their displeasure) and the fruits of Falkan's own discoveries, they are formidable, even monstrous, killing engines. Like the Thallax, Ursarax are true thralls rather than Servitors. Selected from suitable human candidates for conversion, their living components retain a consciousness and dim recollection of their former humanity, providing them with superior tactical abilities and the instincts to kill. Neural anesthesia is automatically administered for their successful fulfillment of their orders, providing them with relief, albeit temporarily, from their tortured existences. After Falkan's mysterious disappearance his warring acolytes dispersed to many different masters, taking the secret of the Ursarax's creation with them.

Ordo Reductor Technology

  • Land Raider Achilles - The Land Raider Achilles originated in the closing years of the Great Crusade. The Achilles Pattern is perhaps the rarest and most venerable Land Raider variant still used on the battlefields of the late 41st Millenium. It was originally created by the Imperial Fists Legion in response to a dire xenos threat now lost to the mists of history, and is fittingly rare outside the armouries of the Imperial Fists, their Successor Chapters and the Ordo Reductor of the Adeptus Mechanicus.
  • Siege Wrecker - A Siege Wrecker is a general term given to a specialised form of massive close combat weapon intended for use by robotic Mechanicum battle-automata which are utilised by the Ordo Reductor. Wreckers are designed to enable these heavy assault units to smash through fortifications and easily crush armoured barricades and defences in siege warfare. The most common form of this weapon is a hydraulic ram or massive disruption-field augmented hammer, although specialised forms of heavy claw or drill systems are also used.

Heraldic Devices of the Ordo Reductor

Lorica Thallax Lacrymal-XVII Pattern Encapsulation

Thallax Omicron-765: Lorica Thallax Lacrymal-XVII Pattern Encapsulation; Cohort Deployment with Clan Avernii of the Iron Hands Legion at the Drop Site Massacre

The various arms, sects, cults and factions of the Mechanicum commonly display heraldry of widely varying degrees. To outsiders a great deal of the nuance, symbolism and application of these signifiers is lost, shrouded by the arcane doctrines and circles of the Cult of the Omnissiah's worship, but the broadcast and most general interpretations are widely understood. In many such sects of the Mechanicum, the deep crimson livery most associated with the Machine Cult is in fact reserved most often for its sworn and initiated priesthood: the Magi, ordained Enginseers, logisters, autosavants and so on, and by lessening degree their initiates and close retainers. The bulk of the Mechanicum's soldiery, however, as well as their laymen servants, are usually clad in darker hue, often of a livery associated with their Forge World or particular order, but marked always with the heraldic device of their masters.

Such is the common case with the Thallax. Where in service with the Ordo Reductor directly, it is common for the Thallax's armour and limbs to be over-plated with either burnished steel, polished bronze or, more rarely, gold or some environmentally protective coating. This is further adorned with colouration and iconography marked upon one or both pauldrons and/or more rarely the breastplate featuring the heraldry of their order of service, cohort designation, Forge Stamp and issue. During the Great Crusade and early Horus Heresy era, where the Ordo Reductor unit had been embedded for a time of service with a particular Space Marine Legion, Rogue Trader Militant, Titan Legion or Imperial Army Battlegroup, it was often customary to adopt in part the heraldry of that larger formation, and often for the Broken Tower emblem of the Ordo Reductor to be heraldically parted with the symbol of the principal affiliation, as shown with the following examples:

Thallax Heraldry Examples

Example Thallax Cohort Heraldry of the Ordo Reductor

Top Row (from Left-to-Right):

Bottom Row (from Left-to-Right):

  • Ordo Reductor/Word Bearers Legion; Gravis Logos-Nul Cohort
  • Ordo Reductor Phaeton Sigma-5-Osedax Cohort



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