"It is a plague of Chaos."
The veterans were altogether too familiar with the foul stench that practically seeped through the seals of their power armor. This was the work of Nurgle.
Plop.
The jungle floor was a labyrinth of stagnant, bog-like mires. Occasional gasps of expanding gas broke the surface of the mud, releasing bursts of vapor as though something foul were breathing just beneath the sludgy depths. Rot-flies buzzed in dense, droning swarms through the warped undergrowth. Scattered everywhere were misshapen skeletal remains, evidently the original inhabitants of this world.
Thud!
A plague-beast, resembling a living mass of putrid sludge, lunged from a nearby mire. It let out an unnatural, gurgling screech as it closed in on a scout's visual blind spot.
A battle-brother flanking him reacted instantly, raising his bolter and opening fire. The bolt-shell detonated squarely within the plague-beast's cranium, sending chunks of corrupted flesh splashing in all directions.
Yet, the sharp report of the bolter immediately drew the attention of other horrors prowling the brush. A massive pack of hound-like entities broke from the treeline, lunging at the vanguard team. These warped monstrosities stood nearly a meter and a half tall, their bodies marred by weeping, necrotic gashes. Clusters of raw, newly sprouted flesh-buds and jagged bone-spurs bristled from their open wounds, which were completely carpeted by swarms of bloated flies. Through tears in their sloughed hide, clumps of fat maggots could be seen writhing within the meat. It was an abhorrent spectacle.
The White Scars swiftly formed a defensive ring. Their bolters barked in rhythmic unison, throwing up a wall of muzzle-flame that cut down the charging beasts, but the sheer weight of numbers allowed the pack to press closer.
Suddenly, one warrior's bolter jammed, the weapon's casing had been splattered with virulent fluids during the melee, and the metal was already rapidly corroding. A plague-hound seized the moment to leap at him. The legionary drew his combat blade with lightning speed and drove it deep into the creature's throat, triggering a fountain of oily, green pus.
Yet, a mortal strike meant nothing to a creature sustained by Nurgle's rot. Snapping his ceramite-gloved hand forward, the warrior gripped the hound's bone-spurred skull and tore it clean off the spine with a sickening crunch. He hurled the severed head at another approaching beast. Driven by the transhuman strength of a demigod and the servo-motors of his power armor, the skull hit like a cannonball, shattering the second hound to pieces.
With his primary bolter rendered entirely useless, the warrior drew his heavy dao blade to face the horde in close quarters. The unnatural resilience of these plague-spawned horrors was rapidly draining the vanguard's limited ammunition reserves.
Worse still, the continuous thunder of bolter fire had finally alerted the true master of this domain.
Boom! Boom! Boom!
A heavy cadence of gunfire erupted from the depths of the twisted jungle. A devastating hail of bolt-shells tore through the canopy, shredding the remaining plague-beasts and the White Scars alike in a single, blind salvos. Over half the remaining warriors were cut down in the opening seconds of the ambush.
Those who survived were instantly cast into a desperate bid for survival. The incoming fire had compromised their armor integrity; the vacuum seals on two warriors' helmets were shattered. On an ordinary battlefield, a breach in the atmospheric integrity was a minor complication, but here, the air itself was a concentrated vector of warp-plague.
Thud. Thud.
Heavy, deliberate footsteps echoed from the depths of the trees. The surviving legionaries felt their lungs burning, their breath growing agonizingly shallow. A sudden, unprecedented weakness spread through their limbs, the unmistakable sign of Nurgle's rot aggressively breaking down their transhuman biology.
A few veterans whose armor seals remained intact maintained a steady stream of fire toward the oncoming sound. However, their power armor systems were stuttering; auspex arrays blinked into static, and the tactical displays on their retinal feeds began to tear and distort.
Recognizing that their compromised helms had become liabilities, the White Scars tore them off and drew their long blades, opting to meet death face-to-face. Yet, without the filters of their armor, the warp-plague flooded their systems with terrifying speed.
The heavy footsteps suddenly accelerated into a blur of motion. Two massive figures erupted into the Scars' failing vision.
With a blinding flash of rusted iron, several bearded heads flew into the air.
In moments, only two White Scars remained alive on the field, their bodies completely paralyzed by the systemic failure brought on by the atmospheric plague. Through their fading consciousness, they felt themselves being hoisted into the air as effortlessly as discarded rags.
A sudden, sharp agony in their midsections jolted them back into a brief state of lucidity. Massive, rust-pitted scythes had impaled both legionaries through the torso, lifting them high off the ground.
"What business have the primitive, witless savages of the plains on this world?"
A grating, hollow voice rumbled through the plague-choked air. The two dying White Scars finally locked eyes with the towering figure before them.
The entity wore heavy, voluminous robes of a sickening yellow-green hue, encrusted with filth, mold, and systemic rot, its tattered hems dripping with a viscous, foul-smelling slime. Beneath the rags, plates of unholy, bone-like armor showed a coarse, irregular texture, pitted and scarred as if fused together from the remains of a thousand different corpses. Malignant green gemstones were embedded within the plates, pulsing with a pale, baleful light. A tattered, threadbare cloak trailed behind him like a funeral shroud, stirring a localized mist of grey vapor laden with withered briars, crawling maggots, and trails of wet slime.
But it was the massive scythe, far larger than those carried by the other traitors present, that instantly revealed the monster's identity to the dying loyalists.
"Mortarion!" one of the White Scars spat, choking on his own blood. "Traitor to the Throne! Lackey of Chaos!"
The eagles of Chogoris bowed to no foe, even when death held them in its teeth.
The lethal payload of the warp-plague was already cascading from the blades impaling them, rotting their organs from the inside out. Holding the scythes were two silent, imposing terminators of the Deathshroud. Perhaps insulted by the vitriol directed at their gene-sire, the two bodyguards subtly jerked their massive hands. The crescent blades sliced upward through the loyalists' torsos, splitting their bodies nearly in two.
As the ruined husks fell to the muck, the spilling transhuman blood visibly curdled into a dark, stagnant green, releasing the stench of instant decay. A cluster of anomalous, pale fungi erupted from the fresh, ruined meat, growing, withering, and bursting in a matter of seconds to scatter a fresh cloud of pathogenic spores.
True to their ancient traditions, the Primarch's elite guardians remained utterly mute.
Mortarion had clearly expected nothing of substance from these doomed captives anyway. He turned his face toward the sky, peering through the heavy curtains of toxic smog.
"The Sacred Number has manifested," Mortarion murmured, his eyes burning with a dark, obsessive intensity. "According to the principles of numerology, victory shall be mine in this cycle."
Deep within the shifting currents of the Immaterium, Kairos Fateweaver watched the Daemon Primarch through a hairline fracture in reality, a mocking, dual-toned cackle echoing from his avian beaks.
Aboard the flagship, Jaghatai Khan felt a cold spike of dread settle in his chest. Hours had passed without a single whisper of vox traffic.
With two successive vanguard detachments vanished without a trace, Jubal Khan, his transhuman body fully reconstructed and forged stronger than ever before, stepped forward, requesting permission to personally lead a heavy strike force down to the surface to uncover the truth.