Malygrisian Tech Heresy
The Malygrisian Tech Heresy is a notable event that originated within the Calixis Sector, accomplished by the renegade Tech-Priest Umbra Malygris. His actions led to the spread of a tech-heretical cult within the ranks of the Adeptus Mechanicus which grew around three centuries ago in the Malfian Sub-sector. The many crimes against both Imperial law and the tenets of the Cult Mechanicus included the creation of experimental viral-strains, vivication of corpses and even the forging of forbidden Silica Animus. Ultimately, Malygris the Damned and his followers, the Malygrisians, were tracked down and eliminated by the joint work of the Inquisition and the Cult Mechanicus.
Following the completion of that task, a purge was conducted of all the lore that had been conducted by this Tech Heresy. However, despite their actions, elements of this knowledge persisted within the minds of those Tech-Priests sent to wipe it from existence. Such individuals are tempted in the same way as Radical Inquisitors are when finding dark knowledge and seek to use it against their enemies but risk damning themselves as well as being persecuted by their own Puritanical brethren. Certain Inquisitors seek to add Malygrisians into their cadres in order to make use of their talents against the dark forces that challenge the Imperium. However, the very knowledge and science they use make such Tech-Priests ticking bombs.