...
The Next Day
Aside from Qin Mo himself, all five warriors equipped with Thunderborn-pattern warplate had been deployed on deep-strike operations, each sent alone into the most contaminated pockets of heretic-held territory.
That was rare. The Thunderborn were few, their armor difficult to replace, and their missions usually required careful allocation. Sending all five into the field at once meant Qin Mo wanted something done quickly, quietly, and without a conventional command chain slowing it down.
Grot's heavy boots struck the charred ground with dull, rhythmic impacts as he marched beside Grey. His gravitic hammer hung across his back, its power core dormant but ready. His attention, however, remained fixed on the strange weapon cradled in Grey's gauntlets.
It resembled an ignis-pattern flamer at first glance: reinforced barrel, pressure canister, armored feed line, forward grip. But the proportions were wrong. The nozzle was narrower. The canister was sealed too cleanly. Auspex runes on the casing pulsed with sterile blue light instead of the warning-red glow of promethium systems.
"What are the Lord Commander's orders?" Grot rumbled.
Grey did not answer immediately. Qin Mo had entrusted the weapon only to him. He had also given Grey the mission parameters privately and ordered him to relay them once the squad was assembled.
That bothered Grot. It bothered Anruida too, judging by the way he kept glancing at the canister as though expecting it to hiss open on its own.
At last, Grey lifted the weapon slightly.
"The orders are simple," he said. "This device functions similarly to a flamer, but instead of promethium, it projects a specialized liquid compound. Our objective is clear: find the heretics and administer the compound."
For several seconds, no one spoke.
"...Administer?" Grot repeated.
Anruida folded his arms across his chestplate. The movement made the servos in his armor give a faint mechanical whine. "So this is a field test for a new weapon?"
"Yes and no." Grey shook his head. "The Lord Commander says the weapon is already in its final iteration. We are not here to test whether it functions. We are here to use it and observe the results."
That answer did not reassure anyone.
Thunderborn wargear was usually direct in purpose. Shields stopped bullets. Hammers crushed armor. Lascannons burned holes through tanks. Qin Mo's inventions could be strange, but they rarely sounded so deliberately evasive.
After a long pause, Anruida voiced the obvious problem.
"This weapon is clearly designed for purging heretics," he said. "But why use it on individual targets? At best, we'll kill a handful. What purpose does that serve?"
Grey considered explaining more.
Then he decided against it. He was not Qin Mo. He did not enjoy turning every answer into a lesson in applied warfare, biology, logistics, or whatever forbidden category this weapon belonged to. Besides, some truths were better demonstrated than described.
"The Lord Commander authorized us to use it on any heretic we encounter," Grey said. "But I think we'll learn more from a concentrated group. Preferably one with command value."
Grot gave a low grunt of approval. "Now that sounds like a proper hunt."
Grey started forward.
The others followed.
....
Twelve kilometers later, Grey raised a fist and the squad halted.
Before them stood the crumbling husk of a once-grand structure, half shrine, half administrative hall, now claimed by rot and treason. Its upper windows had been blown out. Devotional carvings had been defaced and replaced with crude symbols painted in old blood, purple pigment, and industrial dye. The entrance doors hung open, but no sentries stood outside.
That alone was suspicious.
Grey's helm display filled with bioscanner returns. Dozens of bodies. Perhaps more than a hundred. Warm signatures clustered together in the central chamber. No patrol pattern. No outer guard. No discipline.
They were all inside. Gathered in one place.
Whatever they were doing, they believed themselves safe.
"Seal every exit," Grey ordered. "No one gets out."
The Thunderborn moved at once. Grot took the main entrance, hammer drawn and power field waking around its head in a low, hungry hum. Anruida and the others crossed to the side exits and shattered windows, weapons raised, armor locking into overwatch posture.
Grey approached the nearest broken window and peered inside.
The heretics knelt in rapturous worship before a towering four-armed effigy. The statue had been carved in the shape of an impossibly beautiful male figure, its features too smooth, too symmetrical, too deliberately perfect. It wore a smile that made the skin crawl. Around its base lay offerings: teeth, ration tins, broken Aquila charms, finger bones, scraps of uniforms, and the blood-slick remains of men who had clearly not volunteered.
The congregation chanted in guttural Low Gothic warped by alien syllables. Some wore PDF coats. Others were mutants hidden beneath robes. A few had extra limbs tucked close to their bodies like shame disguised as devotion.
Grey's mouth twisted beneath his helmet.
"Perfect opportunity."
He stepped into position at the window. Anruida shifted aside without protest, though his visor remained fixed on the weapon.
The Exterminator rested against the cracked window frame. Up close, it looked less like a flamer and more like a surgical instrument designed by someone who considered mercy a design flaw. Its feed canister clicked once as internal pressure stabilized. A thin line of blue light ran along the barrel.
For one brief, foolish moment, Grey imagined what it might do.
Would the heretics burn? Melt? Dissolve instantly into wet stains on the floor? Would Qin Mo's compound eat through flesh, bone, and mutation alike?
"Stop fantasizing and fire the damned thing," Grot growled over the squad vox.
Grey pulled the trigger.
Sssshhht.
A narrow stream of iridescent blue liquid arced through the stale air and struck the exposed back of a kneeling cultist.
The man flinched. His chant faltered. One hand reached back to scratch at the damp patch spreading across his robe. He turned, confused and irritated, toward the window.
His eyes met Grey's visor.
Grey emptied the rest of the canister into the chamber. Blue droplets scattered across robes, skin, stone, offerings, and the polished base of the idol. Then he stepped back.
"Move," he snapped.
Grot turned from the entrance. "We're not going in?"
"No."
"Why not?"
"Because we need to see what it does."
The first scream rose inside the shrine. Not pain. Alarm.
Then the heretics saw them.
The congregation broke apart in an instant. Worship turned to rage. Cultists hurled themselves toward the exits, howling devotion and threats, some dragging weapons from beneath their robes, others simply clawing at the air with mutated hands.
Grey did not let them reach the squad.
He led them away.
It was not a retreat. It was a controlled lure. He kept just far enough ahead that the cultists believed they could catch him, letting them spill into the open streets in a disorganized mob. Grot muttered complaints the entire time, but he followed. So did the others.
"Why aren't we just purging them outright?" Grot demanded.
"Because the Lord Commander did not build this weapon for ordinary killing," Grey replied. "Watch them."
They ran for several minutes.
Then the first cultist stumbled.
His stride broke into a jerking, uneven lurch. He tried to keep moving, but his legs began to swell beneath his robes, flesh distending as though thick cables were coiling under the skin. He screamed and clawed at himself. His fingernails tore away.
Another cultist pitched forward, back arching violently. His ribcage expanded with a series of wet cracks, bones snapping outward before his torso ruptured in a spray of blood, tissue, and blue fluid.
A third seized his own face. His skull ballooned grotesquely, skin stretching thin over a swelling mass beneath. His eyes burst first. Then the rest of him followed.
The effect spread through the mob with horrifying speed. Cultists who had not been directly struck began convulsing. Those who had only brushed against the infected clutched their throats. Those who had inhaled the mist near the shrine collapsed as the compound found whatever marker Qin Mo had designed it to hunt.
Bodies bloated. Robes split. Mutated limbs twitched and distended.
Then one burst.
Pop.
The sound was small. Almost obscene in its simplicity.
Another followed.
Then another.
Within seconds, the charging mob ceased to be a mob at all. The heretics burst like overripe fruit, their remains collapsing into slick blue puddles that steamed faintly against the ash-covered ground.
The Thunderborn stood in silence.
"By the Emperor," Anruida whispered.
Grot stared at the spreading blue pools. His earlier irritation faded into open calculation. "If we mass-produce this and integrate it into flamers, we could clear entire structures without losing a man."
Another warrior gave a low, uneasy laugh. "Assuming it doesn't clear the wrong structure afterward."
The squad began discussing range, delivery systems, battlefield use, decontamination protocols, and whether the compound could be deployed through drones. Their voices carried the excitement of soldiers who had seen a weapon that could erase the enemy without risking friendly lives.
Grey remained silent.
He was replaying the bioscanner data in his mind.
He had sprayed only a few cultists directly.
Yet every life sign inside the building had vanished. Not reduced. Not scattered. Gone.
Even those who had never left the shrine were dead.
The weapon had not merely killed exposed targets. It had propagated.
Grey turned back toward the shrine. Blue residue trickled down the broken steps like spilled paint. The idol inside had cracked from heat or chemical reaction, its perfect smile now split through the middle.
Grey's voice was quiet when he finally spoke.
"This weapon is far more potent than anticipated. This will be our first and last time using it."
Grot barked a laugh. "Because we've wiped out all the heretics in this sector, right?"
Grey did not answer.
He simply turned and led the squad back.
....
On the transport back to base, no one dwelled on Grey's warning.
The cabin vibrated beneath them as the craft skimmed over the broken battlefield. Below, trench lines, burned hab-blocks, wrecked vehicles, and corpse-choked avenues slid past beneath layers of smoke. The Thunderborn reviewed their combat recordings, already imagining how the Exterminator might change siege warfare.
Grot sat near the open side hatch, one armored hand braced against the frame. He was watching the ground below when he saw it.
A lone heretic foot soldier staggered between two ruined barricades. He was far from the shrine. Far from the target area. He clutched his rifle in both hands and moved with the hunched exhaustion of a man trying to return to his unit.
Then he convulsed.
His body swelled. His armor straps snapped. A heartbeat later he exploded into blue liquid.
Grot blinked.
For a moment, he wondered whether the smoke, fatigue, and battlefield glare had tricked his eyes.
Then another heretic burst near a crater.
Then another.
And another.
Blue stains appeared across the battlefield like sudden, blooming wounds.
"Wait," Grot said slowly. "Is someone else using the Exterminator?"
"No," Grey replied.
His tone made the others turn.
"We were the only ones issued the prototype."
Grot looked back down at the spreading blue marks below. For once, he said nothing.
Deep thought settled over him like armor heavier than his warplate.
....
Two Days Later
Deep within the fortress, Qin Mo sat in his command chamber and reviewed the latest intelligence reports from the front.
The chamber was quiet except for the low hum of cogitator banks, the soft click of data-slates updating, and the distant vibration of industry from the fabrication levels below. Hololithic projections hovered around him in layered sheets: battlefield maps, casualty estimates, drone feeds, chemical spread models, and reports flagged by the AI Core for command review.
Every frontline regiment was reporting the same phenomenon.
Cultists were dissolving mid-battle without visible cause. Mutants collapsed during assaults. Xenos-tainted creatures burst apart inside tunnel networks no Thunderborn had visited. In freshly secured zones, heretic shrines, abandoned dwellings, and barricaded hideouts bore the same evidence: blue residue, ruptured bodies, and no sign of direct attack.
The Exterminator agent was working.
Too well.
There was no need for further adjustment. No need for mass deployment. No need to risk soldiers carrying canisters of a compound that clearly did not understand the concept of a local engagement.
The only thing left to do was wait.
The heretics were vanishing on their own.
That should have satisfied him. It did not. Qin Mo had long since learned that a weapon which solved one problem usually revealed three more. The Exterminator could purge a contaminated population, but it was not the answer to everything hiding in the dark. It would not stop sorcery. It would not prevent mental domination. It would not explain why the Warp continued to intrude upon every rational system he built.
So Qin Mo turned his attention to anti-psyker technology.
And for that, he had the perfect test subject.
Vanessa.
The captured psyker.
....
Beneath the fortress, in a sterile containment chamber carved from reinforced metal and warded stone, Vanessa lay strapped to a surgical slab.
The room had been built for control rather than comfort. Restraint arms locked her wrists, ankles, shoulders, and throat in place. Auspex arrays hung over her body like insect limbs.
Sensor needles rested against skin but did not pierce unless ordered. Hexagrammic seals had been engraved into the floor and walls, not because Qin Mo trusted them completely, but because redundancy was never wasted when dealing with psykers.
Vanessa's eyes, however, remained bright with amusement.
"So tell me, Lord Qin Mo," she murmured, as though they were sharing tea instead of preparing for invasive experimentation, "how does your Exterminator work? Why does it spread so quickly? Why don't the heretics isolate the infected?"
Qin Mo barely glanced at her.
He already disliked psykers. Their existence offended every clean line of cause and effect he preferred. A psyker was a biological breach point, a person-shaped risk assessment with emotions, opinions, and the potential to turn a fortress into a daemon-infested slaughterhouse if frightened at the wrong moment.
A talkative psyker was worse.
Vanessa smiled, sensing his irritation even without reading his mind.
Qin Mo ignored her and focused on the data scrolling across the console. The bio-scan updated in real time, feeding genetic, neurological, and metabolic readings into the cogitator banks. The system mapped Vanessa's nervous activity, endocrine response, pulse irregularities, and every measurable fluctuation that might correlate with psychic exertion.
The problem was obvious.
The machine could measure her body.
It could not measure the Warp.
"You're brilliant in biology, engineering, materials science, weapons design, logistics…" Vanessa tilted her head as far as the restraint allowed. "Everything you touch turns into something useful. Something dangerous. Something better."
Qin Mo's jaw tightened.
"But when it comes to the Warp?" Her smile widened. "You're blind."
The console reflected a faint glimmer of light across Qin Mo's eyes.
"Shut up, witch."
Vanessa laughed softly. The sound was dry, but not frightened. That annoyed him more. Because the worst part was that she was right.
Qin Mo had knowledge. Fragments from another life. Lore, names, warnings, patterns. He knew what the Warp was supposed to be. He knew what psykers could become. He knew the categories of disaster that began with one unstable mind and ended with entire sectors screaming.
But knowing a thing from stories and understanding it as a system were not the same.
He understood matter. Energy. Machines. Biology. Gravity. Heat. Cause and effect The Warp refused to behave like a proper part of the universe.
Vanessa watched his silence and recognized the opening.
"Let me teach you."
Qin Mo gave a short, humorless scoff.
"Get lost. I'm not interested in your heretical nonsense."
Vanessa's smile did not fade.
"No," she said softly. "You're interested. You just hate that I'm the one offering."
Qin Mo finally looked at her fully. The chamber grew quieter. Even the cogitator clicks seemed to recede beneath the weight of his attention.
Vanessa lay bound beneath the scanners, helpless in every physical sense, yet still carrying herself like someone who believed she possessed the one tool he lacked.
Qin Mo despised that confidence.
He also could not afford to ignore it.