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"The path of the Omnissiah has left humanity dithering in the darkness, incapable of advancing on the paths of knowledge. Embracing the Warp reveals technology that the primitives on Mars could never dream of wielding."

— Magos Caine of the Five-Fold Path

A Heretek of the Dark Mechanicum displaying Chaos mutations.

Heretek is the name given by the Adeptus Mechanicus to those tech-priests who turn their backs on the teachings and strictures of the Cult Mechanicus in pursuit of usually dark and forbidden technologies linked to the power of the Warp and the Ruinous Powers of Chaos.

Hereteks value the pursuit of knowledge, of any knowledge, at all costs, regardless of the consequences to themselves or to others and even at the peril of their own souls.

Many Hereteks are loosely connected to the Dark Mechanicum, those members of the ancient Priesthood of Mars who turned their backs upon the Emperor of Mankind during the Horus Heresy and the Schism of Mars and swore to serve the Warmaster Horus and the Dark Gods in return for technological advancements denied them by the Emperor for the safety of Mankind.

Others, however, pursue the dark path of tech-heresy completely on their own, forging their own roads to damnation independent of any direct connection to Chaos or the Dark Mechanicum, though still wholly in violation of the strictures of the Cult of the Machine God.

Hereteks discovered or captured by the Mechanicus are either executed outright or have all of their cybernetic implants painfully removed and their organic remains transformed into a mindless servitor as penance for their tech-heresy.


A Heretek of the Dark Mechanicum

At the very start of the Great Crusade in ca. 800.M30, the Emperor signed a defining agreement with the Cult Mechanicum, the Treaty of Mars, ensuring their much-needed collaboration to prosecute the unification of Mankind.

Having witnessed the corruption and revolt of the Men of Iron millenia earlier during the Age of Technology, the Emperor forbade the ancient Mechanicum, as part of the agreement, to pursue certain theories and avenues of technology like artificial general intelligence that could easily be corrupted by the power of Chaos.

Two standard centuries later, in the depths of the darkest hours of the Horus Heresy, the Space Marine Legions turned against each other. Yet, they were not the only adepta within the Imperium of Man at that time to be torn apart by civil strife.

The Mechanicum, the tech-priests of Mars and keepers of the secrets of Human technology, dissolved into their own civil war that is known to Imperial historians as the Schism of Mars.

The Renegades, bitter about the interference of the Emperor in their sovereignty and the limitations placed upon their research by the Treaty of Mars, sided with the Warmaster Horus, unleashing dark technologies and dabbling in tech-heresy, before finally being driven from Mars by the resurgent Loyalists.

When the Heresy ended in a pyrrhic triumph for the Imperium at the Siege of Terra, the Renegades fled Imperial space during the Great Scouring into the Eye of Terror alongside the Traitor Legions and into other far corners of the galaxy.

There they became the first Hereteks of the Dark Mechanicum, corrupted tech-priests enthralled to the Warp and heretical technologies long-forbidden to the servants of the Machine God.

As these technophiles embraced their new masters and the Chaotic ways of the Warp, they ignored all of the strictures that the Mechanicum had chosen to embrace, largely out of a concern for the safety of Mankind from certain dangerous and corruptive technologies which had previously presented great threats to the Human race's continued existence.

Consequently, the Hereteks' research often extended specifically towards areas that were forbidden to Loyalist tech-priests. These include the development of true artificial general intelligence, the genetics and physiology of the psyker, technology that made use of or manipulated the power of the Immaterium, and investigations of a wide array of xenos technologies.


Because of the nature of their split from the Imperium, these fallen tech-priests lack a central authority or consistent belief structure. As a result, their reigning ideology is far more diverse than that of their former brethren within the Adeptus Mechanicus.

Hereteks may shun the Omnissiah entirely as a false god, worship Him as an extension of Chaos, or simply ignore their former beliefs to focus solely on their research.

Even among the unusually open-minded Explorators of the Adeptus Mechanicus, there are subjects which must be avoided at all cost to remain true to the dictates of the Machine God. A Heretek enthusiastically violates all such strictures, exploring xenos technology, archeotech from the Age of Technology, and dabbling in all facets of technology related to the manipulation of the energies of the Warp.

They may even be bold enough to develop entirely new technologies, combining components in forbidden manners to produce the ultimate tech-heresy for many in the Cult Mechanicus -- innovation. They may go as far as sharing the tools of their trade and the secrets of its ways with those who have not been trained in the mysteries of the Machine God.

A Heretek actively seeks out new technology and continuously experiments with new techniques in ways that were once forbidden. They no longer believe that any information, experiment, or device can be ignored. Rather, they deliberately focus on those technologies that the Mechanicus' teachings taught them to avoid, with a particular interest in developing Warp-based technologies.

Few inquiries concerning technology are beyond a Heretek's interest, though inevitably many of their inventions and much of their research tend towards the development of tools of destruction. As they build these weapons for their fellow devotees, the Heretek has also invariably rebuilt their own body.

It may be that they have few organic components left and those that remain are often marked by the mutational "gifts" of the Chaos Gods. Their cybernetic and sometimes biological enhancements not only improve their technological acumen, they also grant them additional abilities in combat. A Heretek is likely to be much physically hardier as well as much more powerfully armed than even the highest-ranking magos of the Mechanicus.

Some in the Imperium think of those referred to as Hereteks to be a unified force, like the Adeptus Mechanicus itself. This is not the case, as there is no galaxy-spanning organisation dedicated to tech-heresy, including the Dark Mechanicum, which is often treated erroneously as being a monolithic entity like the adepta from which it schismed.

Rather, there are countless fiefdoms and Dark Forge Worlds or Hell-Forges, each ruled by a fallen magos (or several magi) powerful enough to dominate cadres of their fellows and enslave Mechanicus thralls and servants.

Just like the warbands of the Traitor Legions and the other servants of Chaos, the corrupt tech-priests war amongst each other, or prefer to exist aloof from all of their fellow servants of the Dark Gods.

Hereteks often follow a path of constant innovation. A Heretek may be capable of drawing power for their devices directly from the Warp and controlling them with summoned Warp entities. They might dabble with concepts of artificial intelligence, memory transference, or even attempt to capture and preserve the souls of sentient beings within their devices through their arcane knowledge of the Warp.

Many of these inventors mindlessly hew to the idea that the new and the novel is always preferable for accomplishing a given end as established techniques. For them, the joy of a new idea or the recovery of an unknown bit of knowledge is a triumph, even if that idea has already been made obsolete.

With each new advancement, their passion for further such successes grow as does their appetite for ever more knowledge, regardless of its source.

The Heretek is often driven by their hunger for knowledge and is quite willing to use the Ruinous Powers and their daemonic servants as a source. At other times, they seek out xenos technology and archeotech.

They may even coordinate raids upon Imperial strongholds for the sole purpose of recovering their records of where such devices can be found. In many Hereteks' minds, there is no greater purpose in life than serving the cause of the advancement of technology and knowledge. Any sacrifice is justified in the pursuit of this end.

It is relatively rare for a Heretek to be raised by the Dark Gods as a Daemon Prince. All too often, Hereteks end up as a component of one of their own inventions, with too little left of the original body or its personality to even receive such a reward from the Dark Gods.

However, those few who are granted this gift continue to spread their Chaos-tainted technology across the galaxy.

Hereteks in the Galaxy

A Heretek attended by his Servo-skull familiars.

Hereteks come from any place in the galaxy where the Adeptus Mechanicus operates.

Some of the most common origins for Hereteks include the following:

  • Forge Worlds - As the primary worlds of the Priesthood of Mars, the majority of Hereteks begin their careers within the hierarchy of the Adeptus Mechanicus on the Forge Worlds of the Imperium. Though the adepts of these worlds work to apply the Cult Mechanicus' dogma in all that they do, there are those tech-priests who always rebel against such constraints upon their thought. A Heretek who hailed from a Forge World may well have succumbed to the lure of Chaos while researching sequestered knowledge from the dark days of the Horus Heresy and the schism in the ancient Mechanicum, or even forbidden research from the Age of Technology. Such Hereteks likely to focus on finding forbidden artefacts and the knowledge required, expand upon the sanctioned research which led to their banishment.
  • Explorator Fleets - Adeptus Mechanicus Explorator fleets travel deep into the remaining unexplored regions of the galaxy seeking out lost knowledge, particularly Standard Template Construct (STC) databases from the time of the Age of Technology. Explorator Magos are already predisposed to curiosity and easily tempted into exploring forbidden secrets. Chaos-corrupted or xenos technology often holds an unhealthy fascination for them and it is easy for one of their number to discover something that can begin his march to damnation. Hereteks who follow this path are likely to be dominated by their curiosity for all the wonders that the galaxy holds.
  • Forgotten Worlds - There are worlds across the galaxy, such as the War World of Zayth in the frontier region of the Koronus Expanse or worlds in the Jericho Reach, where the local strain of Mankind has been out of contact with the Imperium for many millennia, and the local Mechanicus representatives have been corrupted by innovation and unrestricted thought. Such experimentation may lead entire planets of these technological devotees along the path of Chaos. Individuals who hold these free-thinking beliefs might also beseech the Ruinous Powers for protection when their heretical ways are discovered by the Imperium and persecuted.
  • Hell-Forges - There are Forge Worlds in the galaxy that have fallen to Chaos, becoming feudal bastions dominated by the pursuit of forbidden knowledge and the development of dark technologies. A Heretek from these Forge Worlds will be uninfluenced by the stifling strictures of the Adeptus Mechanicus and will hold radical beliefs on the nature of the Machine God and its relationship with Chaos. They are likely to be the most terrifying of Hereteks, to the point that many are no longer even recognisable as human. Their research may be completely esoteric or it might be so focused on the pursuit of the individual paths of the Chaos Gods that any who made use of it would be overwhelmed by sheer corruption.


  • Black Crusade: Core Rulebook (RPG), pp. 64-65
  • Dark Heresy: The Radical's Handbook (RPG), pg. 44