Heretek

''“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

Heretek is the name given by the Adeptus Mechanicus to those Tech-priests who turn their backs on the teachings 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. Most Hereteks are loosely connected to the Dark Mechanicus, those members of the Priesthood of Mars who turned their backs upon the Emperor of Mankind during the Horus Heresy 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.

History
More than ten millennia ago, in the depths of the darkest hours of the Horus Heresy, the Legions of the Space Marines 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 Adeptus Mechanicus, 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 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 Battle 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 Mechanicus, 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 Adeptus Mechanicus 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 humanity, such as the development of true artificial intelligence. Consequently, the Hereteks' research often extends specifically towards areas that were forbidden to Loyalist Tech-priests. These include sapient technological artefacts, the physiology of the psyker, the ways of the Immaterium, and the vast array of xenos technologies. Because of the nature of their split, these fallen Tech- Magos lack a central authority or consistent belief structure. Because of this, their ideology is far more diverse than that of their former brethren within the Adeptus Mechanicus. Hereteks may shun the Omnissiah as a false god, worship him as a part of the Ruinous Powers, or simply ignore their former beliefs to focus on their research.