Though they possess a once-human brain like all servitors, the Kataphron Battle Servitor has been severed from all emotion and independent thought, and serves as little more than a living weapon controlled by the orders of the Mechanicus' Tech-priests.
They are much larger and more powerful than the standard servitors employed for multiple tasks across the Imperium of Man.
There are two variants of the Kataphron Battle Servitor normally employed depending on the tactical objective of the controlling Tech-adepts -- the Kataphron Breacher and the Kataphron Destroyer.
The servitor complement of even a single Forge World will typically number in the tens of millions. Many were once wanted criminals -- hard and intimidating men from all walks of Imperial life, from hive city gangers stitched with vat-grown slabs of muscle to Inquisitorial enforcers that committed bloody murder after learning too much.
Smuggled into the shipments of raw materials traded between planets of the Imperium and the Forge Worlds, payloads of human cargo are not uncommon, providing another source of flesh that can be used to good effect by the Tech-priests.
When the Adeptus Arbites find and condemn a transgressor of surpassing physical size, that individual will be beaten senseless with Power Mauls and sent battered and bloody to the nearest Forge World. There he is given a second chance to serve Mankind as one of its most faithful servants.
First the specimen is mind-wiped, chemically lobotomised so that his personality and memories are a blank slate -- in theory at least, for there have been numerous cases where some residual traces remained. Next his arms are cut away, usually replaced with weapons or tools suited to the new role his masters have chosen for him.
In the case of Battle Servitors like the Kataphron, the specimen will be halved at the abdomen and permanently sutured and neural-cauterised into a tracked motive unit. His mind will be hardwired with targeting Cogitators, and his voice box surgically modified to better sing binharic praise to the Machine God. The process is of course painful in the extreme, but then no atonement is ever truly complete without sacrifice. And no sacrifice is too great for the Omnissiah.
A Tech-priest Dominus can call upon a body of Battle Servitors to protect him in battle. Among the largest and most potent of these living artillery pieces are the Kataphron Breachers. Kataphron Breachers are Battle Servitors many times the size and power of those used by the rest of the Imperium.
Utterly deadly at close quarters, they are not born so much as constructed, their every enhancement geared for maximum lethality. They are easily recognised by their growling motive units, vicious hydraulic pincers and deadly shoulder-mounted cannons.
Yet the most vital component of all is within -- the soul of a violent man. Many of the fleshy components of servitors are vat-grown, but it was soon discovered that these artificial organics were unable to bond properly with the hulking machinery of the Kataphron Breacher. After some experimentation, it was found that the constructs only worked properly when centred around the soul of what was not just a living man, but a particularly violent one.
The part of the Kataphron Breacher that was once human shows no emotion, but will respond by rote to the binharic imperatives of the Tech-priests. The process of being turned into a Battle Servitor preserves something of the pugnacious spirit, however, and the promise of slaughter seems to accelerate the bulky man-machines.
In battle Kataphron Breachers rumble forward at the command of their Tech-priest masters, fulfilling the role of living shield and battering ram alike. Originally devised to break apart enemy battle lines and fortifications, they are of great use to those adepts who wish to seize a valuable artefact from the clutches of would-be usurpers. As they near the front line the volleys levelled by the foe thunder around the Breachers to little effect; the thick overlapping plates that cover the flesh-parts of the Battle Servitors make them all but invulnerable to small arms fire.
Once their proximity bells chime, Breachers return fire with helical blasts of energy from Heavy Arc Rifles or the twisting, ripping fields of Torsion Cannons. Whilst the foe scatters in disarray the Breachers accelerate, crashing into enemy lines to crush and kill with piston-driven talons and coruscating Arc Claws. At the whims of Tech-priests, cities and even entire worlds have been ground to dust beneath the remorseless tracks of these half-creatures.
Though Kataphron Breachers are potent, they are easily replaced and can be mustered in the thousands if necessary. All Forge Worlds create these half-machine war constructs on a daily basis, their biohangars stacked with rank upon rank of dormant Kataphron Servitors awaiting the binharic command to awaken.
In battle they are used callously, and unlike the relic robots of the Legio Cybernetica, the mangled remains of destroyed Kataphron Breachers are regarded as nothing more than scrap metal. Their survival is of little import, and a Tech-priest will expend them with no more thought than a Space Marine would expend a clip of Bolter shells.
"The basilica wall gave way with a landslide crash. A gigantic bio-beast shouldered through it, thick knots of lesser Tyranids spilling through amongst the rubble and clouds of ancient brick dust. The Cognis weaponry of Destroyer-clade Vho-9-Rhombus reacted before the Servitors themselves, snapping round to belch great clouds of Promethium flame into those weapon-beasts skittering forwards. As one, Vho-9-Rhombus pivoted and slowly reversed, the expressions of the three Battle Servitors as slack and disinterested as if still in transit to the war zone. The spindly servo-limbs of their Cognis Flamers deftly detached the empty canisters and replaced them without a microsecond of hesitation. Tyranids leapt, blade-arms whipping through the air, only to be caught once more in blasts of flame. The giant wrecker organism barrelled through the fires with a screeching roar, a crab-like pincer crushing the leftmost Battle Servitor in an explosion of sparks and stinking blood. From the nave behind came a monotonous chant, the sound filling the basilica's perfect acoustics with binharic battle cant. The two remaining Kataphrons shook as if in ecstasy before levelling their Graviton Cannons at the beast ploughing through the pews towards their master. The Tyranid creature screamed as its carapace cracked in a hundred places, and then it burst, squashed like an insect under the Omnissiah's iron heel."
The cyborg horrors known as Kataphron Destroyers exist only to kill. There is perhaps no purer calling in all the galaxy than that of the living weapon, especially one unsullied by the responsibility of morality, or even thought. All servitors are ultimately only tools wielded by the hand of another, and the Kataphrons are no exception. When such a Battle Servitor is controlled by an Adept of the Machine God, they become destruction incarnate.
Where the standard Kataphron Breacher has at least one clawlike arm, the Destroyer has both its upper limbs replaced by high-yield weaponry. On one side it mounts a cannon of advanced design, ranging from the Heavy Phosphor Blaster -- a weapon that fires white-hot spheres that cling, burning, to the target -- to the Plasma Culverin, a cannon so volatile the servitor's own flesh crisps and burns even as his targets are reduced to molten sludge.
Perhaps most feared of all the Destroyer's tools is the Heavy Graviton Cannon, a weapon that can flatten even the Wraithbone ghost constructs of the Asuryani in a single crushing solar second. Their potential for dealing death does not end there, for on the other side of their torso Destroyers bear secondary weapon systems that can hurl nearby enemies back with roaring gouts of flame and streams of phosphor shot. Those that somehow survive this blistering array of firepower would do well to flee quickly, lest they be ground into the dirt under the Destroyer's heavy tracks.
All Imperial Servitors carry identification numbers, and Battle Servitors are no different. These numbers and the clade or unit to which they belong become their entire identity, their every action driven by their limited programming, for only malfunctioning Servitors develop any sense of self-awareness. A Servitors' functions are rudimentary at best, regardless of its type -- be it a Construction Servitor, Maintenance Servitor, Battle Servitor, or any other configuration.
The cybernetic optics of a Kataphron Destroyer are designed to focus on enemies, allowing the constructs to pinpoint and eliminate viable targets, but due to the limits of their programming, numerous friendly fire accidents have occurred.
During the Third War for Armageddon an enemy-verification error allowed the amassed Kataphron Destroyer clades to turn upon their own allies, mercilessly blasting apart two Imperial Guard divisions and an entire squadron of Leman Russ battle tanks. While most such incidents truly are accidents, some Tech-priests -- the boldest and least scrupulous of their acquisitive kind -- have been known to use the cover of such programming "malfunctions" to achieve their own ends.
Tech-priest Dominus Omingo Sahr was determined that his Requisition Crusade would acquire samples of all the technology it discovered. After his Kataphron Destroyer clade opened fire upon the Adeptus Astartes of the Dark Angels, he was at last able to secure several relic weapons that the Space Marines had foolishly kept from him, even denying that they had such devices in their possession.
- 3-12 Kataphron Breachers or Kataphron Destroyers
- Kataphron Breacherplate - Though the torso and head of the Kataphron Battle Servitor hints at its fleshy past, the rest of its frame is a titanium-laced fortress of metal and plasteel that turns aside bullet and blade alike. Cybernetically reinforced to fit their role as close assault operatives, each Breacher is capable of driving right into the firepower of an entire squad and still emerging intact.
- Heavy Arc Rifle - Devised to slay the daemon machines of the Dark Mechanicum, the Heavy Arc Rifle is powered by ancient Martian electrotech. It sends out shallow parabolas of crackling electromagnetic energy that revolve around each other, forming triple helixes as they blast forth. Should these ground upon a metallic target they will swiftly overload its circuits and banish its animating spirit to the ether.
- Torsion Cannon (Upgrade) - The tri-sectional barrel of the Torsion Cannon is amongst the holiest of Mars' weapon technologies. When energised, it sends out three synchronous graviton gaol-fields that hold sections of the target in place. As the sections of the cannon's barrel turn counter to one another, the matter grasped in the gravitic fields is mercilessly twisted, subjected to an impossible torque that rips, buckles and ruins alien monstrosities and enemy war engines alike.
- Arc Claw - During the Cyberghoul Wars, the burrowing daemon machines of Warpsmith Votogr Bolga were met talon to talon by the Forge World Metalica's Battle Servitor defenders. It was the invention of the Arc Claw that turned the tide -- a potent delivery system for the most sophisticated scrambler technology the Adeptus Mechanicus could devise.
- Hydraulic Claw (Upgrade) - The Hydraulic Claws of Kataphron Breachers are driven not only by powerful pistons, but also sanctified oils that are collected, drip by drip, from Titan God-Machines at rest. The Tech-priests' belief is that in maintaining this process, they confer some of the Titan's strength to their Servitors. One who has witnessed the ruin wrought by a Hydraulic Claw will be hard-pressed to refute it.
- Kataphron Demiplate - The weapon systems of the Kataphron Destroyer generate so much heat that their cabling is necessarily exposed -- to armour their wielder in heavy Breacherplate would doom it to swift burnout. Nonetheless, its cyborg anatomy and heavy steel treads provide a great deal of protection against small arms fire.
- Plasma Culverin - Plasma Culverins sacrifice the range of their cannon pattern equivalents in exchange for a higher rate of fire. Only the Adeptus Mechanicus dare coax such rampant destruction from their Plasma Weapons, yet to the Adepts of Ryza in particular, the scars they leave on wielder and war zone alike are considered quite normal.
- Heavy Graviton Cannon (Upgrade) - The graviton technologies used by the Adeptus Mechanicus are fearsome indeed. A target hit by the Heavy Grav-cannon's invisible field will be stunned and likely crippled, or even crushed under their own exponentially increased mass until all that is left is an oozing disc of biometallic waste.
- Heavy Phosphor Blaster (Upgrade) - Phosphor Weapons range from the hand-held Phosphor Serpenta favoured by many Tech-priests to the Heavy Phosphor Blaster mounted upon Kataphron Battle Servitors. The burning white spheres that shoot out from Phosphor Weapons cling tenaciously to their targets, sizzling wildly as they melt into flesh or burrow through armour and exoskeleton alike. More often than not, it is these luminagenic orbs that deal the death blow. Even if a target proves tough enough to survive the burning pain, the phosphorescent glow these spheres exude can guide an ally's volley to strike the same target.
- Cognis Flamer (Upgrade) - The spark-like anger of the Cognis Flamer's artificially intelligent Machine Spirit has been fanned to a roaring blaze. When under duress it will fight with incendiary wrath, even should its wielder be distracted.
- Codex: Adeptus Mechanicus (8th Edition), pp. 46-47, 76-77
- Codex Adeptus Mechanicus - Cult Mechanicus (7th Edition) (Digital Edition), pp. 64-70, 196-197, 199-200