Heavy, armored footsteps crushed the freezing stone floor as Bill and his surviving battle-brothers marched deeper into the colossal tunnels stretching down toward the core of Pluto. Amidst the oppressive gloom, the only sounds were the rasp of breath through air filters and the low murmurs over the vox-comms. Dark humor and death had become the sole topics of conversation, acting as fragile anchors to hold the frayed sanity of the 9th Legion's warriors together.
Bill swept his gaze through his auto-senses. The architecture of this Plutonian colony was vastly different from the imposing, solemn gothic cathedrals of Terra. It was a decaying relic of the Dark Age of Technology. Steel structures and dead, luminescent circuitry hinted at what "the future" should have been, but it was now overlaid with ruin, soot, and the damp stench of rotting flesh. Millions of the planet's inhabitants had mutated simultaneously in the blink of an eye, victims of a mysterious, inexplicable catastrophe.
"They're coming..." Lysanthus warned over the vox.
At the entrance to the deeper tunnels, a tide of mutants numbering in the hundreds of thousands squeezed and surged forward like a black flood. They threw themselves at the Space Marines in a rabid frenzy, desperate to shred the invaders with their talons and jagged teeth. The brutal clash erupted once more within the suffocating, claustrophobic space.
Though their numbers were fewer than in the open battlefields above, the threat was doubled; the narrow tunnel bottlenecked the lines, forcing them into a desperate, grinding melee. Yet, the Revenant warriors knew no fear. They stood their ground like a wall of living iron. Bolters roared in deafening cadences, punctuated by the high-pitched whir of chainswords severing flesh and unleashing torrents of blood.
The situation began to deteriorate as the mountain of mutant corpses piled nearly three meters high, and Space Marine brothers began to fall one by one. Suddenly, the thunderous roar of jet engines shook the cavern from above. A massive Stormbird gunship hovered overhead, the blistering heat of its thrusters momentarily dispelling Pluto's biting chill before its frontal assault ramp slammed violently onto the ground.
BOOM!
A colossal figure clad in thick, dark-grey armor plunged from the gunship. The sheer kinetic impact and immense weight crushed the mutants beneath like ripe melons under a sledgehammer, sending blood and viscera flying in all directions. The figure sank nearly waist-deep into the mountain of corpses, weighed down by armor several times heavier than that of a standard Space Marine.
Bill's eyes widened behind his visor. It was a prototype Saturnine Pattern Tactical Dreadnought Armour—an archaic, cumbersome relic yet to be refined by the master craftsmanship of Primarch Vulkan of the Salamanders Legion. It resembled a walking fortress with massive, rounded shoulders. It was clumsy in appearance, yet chillingly powerful.
The giant in the Saturnine armor moved slowly but with crushing deliberateness. He swung a glowing blue Power Fist, striking the face of a lunging beast. The molecular-disrupting force of the impact caused the creature's upper torso to vaporize into a shower of gore in a single blow.
Simultaneously, the multi-barreled heavy weapon slung beneath his right arm spun up and let loose a deafening roar, raking the mutant horde with massive armor-piercing rounds. The mutants fell like wheat before a scythe. Any beasts that managed to slip past the gunfire were seized by the left Power Fist and crushed until their bones ground to powder.
The sudden arrival of this mysterious Saturnine Terminator instantly shifted the tide in favor of the 9th Legion. The black claws that had easily shredded the MKII Crusade Pattern armor of Bill's squad could not leave so much as a superficial scratch on the incredibly dense, meteoric iron plating of this lumbering titan.
Snapping back to attention, Bill raised his bolter to his shoulder, providing flanking fire and picking off the smaller creatures trying to scale the giant Terminator's massive pauldrons. In that moment, Bill's twin hearts hammered violently. His hyperextended Astartes reflexes kicked in, slowing down the chaotic world around him to a crawl.
He could see empty brass casings drifting lazily through the air, and watch the micro-rocket bolts of his weapon drill into mutant flesh before detonating their innards. He felt the sharp recoil vibrating through his black carapace and reconstructed bone structure, while the sickeningly sweet, metallic scent of blood leaked through his damaged respirator filters. It took a monumental effort of will to grind his teeth and suppress the Red Thirst boiling in his veins while keeping his aim steady.
As they pushed deeper into the damp, dark subterranean passages, the environment turned into a cacophony of horror. The roar of bolter fire bounced off the concrete walls like endless thunder. Muzzle flashes strobed in the dark, accompanied by the bone-grating shriek of chainswords. Had any Space Marine been without his helmet, the concussive pressure waves would have ruptured their eardrums instantly.
The Saturnine Terminator remained the spearhead. Even after his heavy weapon ran dry of ammunition, he used his massive bulk and Power Fist to shatter any obstacle in their path, his thick grey plating now caked in deep gouges and layers of drying gore.
But amidst the chaos, a mutant of freakish agility scaled the cavern walls, dodging gunfire with unnatural grace. It leapt onto the giant pauldron of the Saturnine Terminator, using it as a springboard to vault over the front line—and lunged straight at Bill, who was providing covering fire from the rear!
"Grayson! Watch out!" Rapha's voice barked through the vox.
Bill tried to sidestep, but he was too slow. The hulking mutant tackled him with immense force, slamming him hard onto the concrete floor. His bolter slipped from his grasp, vanishing into the darkness. Pinned to the ground amidst heaps of flesh and blood, Bill reached frantically for his chainsword or chainaxe, but his fingers clawed at empty air.
Behind his visor, Bill's eyes stretched wide with alarm. He drove his armored fists repeatedly into the creature's grotesque face, but the abomination possessed an unnatural, terrifying strength. It didn't even flinch.
It unhinged its jaw, revealing rows of jagged, pitch-black teeth ready to tear Bill's head from his shoulders. Bill twisted his neck violently, causing the creature's jaws to snap shut and bite down hard on his right pauldron instead.
CRACK!
Its dark fangs and talons punched through the ceramite alloy shoulder guard as if it were parchment. Crimson warning runes flashed frantically across Bill's HUD, reporting critical structural failure to his right pauldron and damage to his Black Carapace interface. Fortunately, the thick composite plating of his armor prevented the fangs from reaching his actual flesh.
The beast thrashed its head wildly, tearing the damaged pauldron clean off Bill's armor. Just as it reared back to plunge its fangs in for a second, fatal strike—
BANG! BANG! BANG!
A burst of bolter shells tore through the beast's head and neck from the flank. Its massive body spasmed violently before collapsing lifelessly over him. Rapha stood a few paces away, smoke still curling from the barrel of his bolter.
"Get up, Grayson!" Rapha stepped forward, hauling Bill to his feet while shoving a salvaged chainsword from a fallen brother into his hand. "Stay sharp, brother. I have no desire to see you join Ricario and Caius just yet."
"My thanks... Rapha," Bill rasped, taking a deep breath and tightening his grip on the chainsword. The dull throb of pain from his ruptured armor only served to send a fresh surge of adrenaline rushing through his veins. Refusing to stay in the rear, Bill charged past the support line and plunged straight back into the violent melee.
VRRRRRRR!
The chainsword's engine screamed to life, its teeth spinning at maximum velocity. Bill swung the blade, brutally cleaving the first mutant in two. Without breaking momentum, he spun, decapitating a second, a third, and a fourth. Both he and his brothers were now so utterly drenched in dark blood that their slate-grey armor was stained a hellish crimson, making them look like demons ascended from the underworld.
Amidst the pitch-black, hysterical slaughter, some of the 9th Legion Astartes began to lose their grip on sanity. Abandoning their empty weapons, they threw themselves into the mutant horde bare-handed, using fists and teeth to tear the flesh of their enemies in a feral madness, before being overwhelmed and dragged down into the dark.
This raw savagery was far more monstrous than anything Bill had witnessed when fighting the Thunder Warriors back on Terra. At least those thunder-born warriors, though volatile and genetically unstable, fought with a sense of martial pride and honor... unlike this endless, twisted flesh-tide in the underworld of Pluto.
The battle in the death-tunnels of Pluto ground on with no end in sight. And deep within the darkness... something far more terrible was waiting for them.