"We still have no explanation for the death of the passenger. The only witness claims the void-lock unexpectedly opened just as that poor soul walked nearby, while the outer lock was also open. For both to be open is impossible when the auspex registers open void against the hull, yet it happened. I doubt we will ever know why he was so desperate to leave that system, though I am relieved he did pay in advance."
- — Captain Artesia Carnelline of the Killian’s Prize
An Acuitor Mech-Assassin is part of an order of assassins within the Adeptus Mechanicus that operates amongst the Lathe Worlds of the Calixis Sector. Acuitor Mech-Assassins are dedicated to the art of death. They answer only to the Magisters Samadhi of their own order, and usually operate according to their masters' will without scrutiny. The Acuity Set of the Lathes, less formally called the Mech-Assassins, are trained in the art of stealth, able to move within plain sight amongst the lay folk throughout the sector, hidden from scrutiny beneath heavy red robes. These executioners are pulled from across the Lathes and beyond, and instructed in secret fortresses scattered throughout the Calixis Sector. Most candidates who are chosen have proven both faithful and capable of using the skills of the Adeptus Mechanicus to deadly effect. Through the mentally recorded data-tracts left by their founder, Magos Samadhi, the Mech-Assassins believe these cogitations guide them to the targets of their wrath and aid them in making short work of those who oppose the rulers of the Lathes and the will of the Machine God.
The Acuitor Set of the Lathes, less formally called the Mech-Assasins, are notorious killers that hail from the Adeptus Mechanicus Forge Worlds in the Calixis Sector known as the Lathes. Though the truth of the origins of the Acuitor Set is scattered throughout the Lathe Worlds like scraps of data disrupted with a ferromagnetic purge, some shadowy records still remain. During the days of the Angevin Crusade, a pious Magos by the name of Samadhi led his modest forces to several key victories in the Mechanicus’ grand campaign against the Adrantians in what would eventually become the Calixis Sector. After the Lathe Worlds were granted to the Adeptus Mechanicus in 380.M39 for their efforts in the Crusade, Samadhi used his new-wrought influence to form a secret organisation. Some stories say that this was with the tacit permission of the already-powerful Lords Dragon, based on a promise of future service to their cause. He then trained and dedicated the members of this sub-cult to the art of eliminating the enemies of the Omnissiah. Samadhi established the hidden fortresses scattered throughout the realm of the Lathes, such as Rasamal on Lathe-Hesh and Tumala in the heart of the shrouded Panopticon, in which his disciples could be sharpened into perfect tools of the Omnissiah and terrifying instruments of death.
It is whispered that, one day, Samadhi himself vanished into the depths of the archive of Tumala, perhaps finally betrayed by the frailty of flesh, or perhaps becoming one with the ancient Cogitators contained in the fortress. No matter the circumstances of his departure, Samadhi’s disciples rallied around the data-tracts that the first Grand Magister of the Acuitor Set left in his wake. His adherents believe that these data-tracts, based on recordings of his own cogitations, contain his ultimate scheme -- a plan in which all disciples participate, but that none fully understand. Decanting his stored knowledge into their own minds, the agents of the Acuitor Set followed in their patron’s footsteps and tirelessly hunted any they saw as obstacles to the goals of the Adeptus Mechanicus in the Calixis Sector. Starting with the first disciples to succeed the patron of the Acuitor Set, all those who have claimed the title of Magister within the organisation have taken on the cognomen "Magister Samadhi" upon their ascension to this elevated rank, and through them, Samadhi’s name has become as Death itself.
In this day and age, the Acuitor Set has quietly expanded, and though its members are still fleetingly rare, there are several worlds upon which they recruit those gifted in treading the Omnissiah’s darker paths. Most of the recruits are already seasoned Tech-priests, those who have already had to call upon their unique skills to slay their foes, either because of battlefield appointments, poor luck, or a logical reason that required violent conflict. After passing rigourous trials, recruits are infused with the data-tracks of the order’s long-missing founder. Though recruits remain individuals, each carries a part of the vast, calculating mind that spun the Acuitor Set into being. With the knowledge contained in the ancient data-tracks, all Acuitor Mech-Assassins can act according to a single, immense plan without ever setting eyes on other agents after their training or even grasping the true extent of the design. The labours of all become one in the shadows, casting the grim silhouette of Magister Samadhi over the Calixis Sector long ages after his disappearance.
Becoming an Acuitor Mech-Assassin
Tech-priests who are chosen to become Acuitors are pulled from across the Lathes and beyond, and instructed in secret fortresses scattered throughout the Calixis Sector, such as Tumala and Rasamal. Most candidates are those who have proven both faithful and capable of using the skills of the Adeptus Mechanicus to deadly effect. To become an Acuitor is to become a part of a pattern greater than oneself, as all members of the Set mentally carry the data-tracts of Magister Samadhi, which guide them to the targets of their wrath and aid them in making short work of those who oppose the Lathes. Those who can survive the weight of the data-tracts and even begin to decipher the ancient, inscrutable memories, become killers of the greatest calculable efficiency and ruthlessness.
So it is that these disguised agents roam the sector, maintaining voidships, repairing Cogitators, unjamming weapons, and occasionally slaughtering their unsuspecting prey. The methods by which a Mech-Assassin can kill are varied; some value a clean kill at a distance, while others prefer to slay with elaborately created traps or carefully scripted malfunctions. There are also those who like to feel the "wet-iron" of their victims run in crimson rivulets down their bladed Mechadendrites. Many Acuitors also train themselves to enter a state of terrible frenzy on command, flooding their minds with the Samadhi data-tracts so that it might guide their movements in the thick of battle. This practice makes them fearless in the knowledge that all proceeds according to the Grand Magister’s plan. These counterpoints -- clinical, razor-sharp forethought, and savage battle-fury -- balance to make a fully trained Acuitor Mech-Assassin one of the deadliest individuals the Lathes have ever honed.
In all cases, however, the sharpest weapon an Acuitor possesses is his mind. Whenever possible, an Acuitor elaborately plans a kill, running simulation after simulation in his augmented cranium and including a wide array of factors that few without the gifts of the Omnissiah could effectively consider. He might stalk his target for months or years at a time, gathering ever more information to be filed away for his grim purpose. An Acuitor Mech-Assassin’s honed, clicking mind allows him to utilise nearly anything as a lethal weapon; steam pipes become a scalding trap to an unwary passer-by, a firearm becomes a timebomb for its user, and an ancient Cogitator becomes a shadowy maze from which a known Heretek’s mind cannot escape, even as his body sits helpless before it. Even if he cannot kill with his surroundings, an Acuitor might depressurise a voidship’s cabin or redirect a reactor’s vent into a nearby air duct, all to force an enemy into a vulnerable position. Infinite possibilities for murder unfold before a member of the Acuitor Sect, and finding the best one for an enemy of the Omnissiah is simply his role in the greater Quest for Knowledge.
- Dark Heresy: The Lathe Worlds (RPG), pp. 30-32