In the cold void above the embattled planet, the Black Expedition Fleet found itself in a dire position—encircled and relentlessly pressed by four Founding Legion fleets. The outcome was no longer in doubt. The Black Fleet teetered on the edge of annihilation.
But the war did not end in orbit.
A transmission from High Command soon reached every regimental leader: the situation on the surface of Vigilus had deteriorated catastrophically, far from improving with the orbital battle's conclusion.
The images they received were harrowing. Whatever victory was gained in space had not stemmed the tide of ruin below. It had, in fact, hastened it.
"Upon the Golden Throne, let all heretics bear witness to our wrath, our might, our Imperium, and the will of the Warning Star! We descend in fury, blades drawn and guns blazing. We are the reckoning. All that Chaos builds shall be ash and ruin. For the Warmaster's vision must be fulfilled."
The words boomed over the vox-channel—Doom's voice, heavy with righteous fury.
At his command, the Imperial fleet disengaged from orbital conflict and initiated full-scale atmospheric deployment, descending upon Vigilus.
This maneuver, while bold, meant sacrificing orbital superiority. The Chaos-aligned Demon Fleet, content to relinquish space, took the opportunity to regroup. The Eye of Terror yawned wider over the world.
For them, Vigilus had become a banquet hall for the Lord of Death—a rotting altar upon which all life would be butchered.
From their hellish command spires, Mortarion and Lorgar observed with cruel satisfaction. Each Imperial soldier that set foot on the planet brought them closer to their true goal. Every loyalist would be swallowed by the dying world—a necessary offering.
The surface of Vigilus was a landscape of industrial nightmares. Life had long since been scraped away, leaving only jagged rock and chemical ruin. Cyclopean manufactorums sprawled across the plains, their furnaces screaming. Smokestacks wider than a Warlord Titan's barrel belched poisons into the skies.
Toxic rivers wound through the charred terrain, the flow thick with alchemical death. It was a realm hostile to all life—even the greenskins, those brutish orks, struggled to survive here. The thick warp-tainted smog fried auspex arrays and severed vox-links. Cut off and maddened, the orks splintered into warbands and wandered the blighted wastelands, blind and raging.
Above, the air was choked with sulfurous storms, and unholy light bled through reality's cracks, painting the fog with shifting oil-slick hues.
And yet, the Imperial fleet pierced this miasma.
Despite the impossible conditions, they managed to lock onto a surviving Imperial fortress bastion buried beneath the rot.
The Doom Slayer—Dukel—and his fellow commanders burned with fury. But discipline remained their cornerstone. They were not berserkers. They were the finest tacticians the Emperor ever forged.
When orbital artillery finally breached the Purifiers' biomechanical defense grid and the Chaos blockade, the strike captains coordinated a planetfall operation with brutal precision.
Specialized strike teams were dispatched to key sectors. These elites would slip past flak barrages and carve through the corruption like a blade. Their objectives: destroy critical infrastructure, sever energy conduits, and cripple the daemon-haunted manufactorums spewing the poisonous fog.
To shift the tide, the Dark Angels themselves sanctioned the use of forbidden munitions—relics sealed away since the Horus Heresy. They would soon be unleashed with lethal intent.
Once surface targets were neutralized and anti-air batteries silenced, the Astartes fleet would rain divine annihilation.
Though none yet fully grasped what lurked within the heart of the mist-shrouded planet, all believed one thing:
It would burn.
The sky tore asunder as thousands of Imperial transports, marked with the Aquila and Skyhawk insignia, screamed through Vigilus's poisoned skies.
Beneath the noxious cloud layers, horror awaited. Charred, skeletal trees stretched like claws toward the heavens. Rivers ran thick with iridescent toxins and bubbling green sludge.
Even battle-hardened Astartes faltered for a moment, stunned by the sheer blasphemy of the landscape. This was not merely a world touched by Chaos—it was devoured by it.
As the first boots touched the ground, they were met by a deluge of chemical artillery.
Autoturrets fashioned from corpses pivoted in unison, loosing waves of rockets and daemonic energy at descending gunships. Corpses animated by the Purifiers surged from factories, driven by warp sorcery and disease.
Many drop ships were torn from the skies, engulfed in flame. Yet the soldiers within—Astartes, unbroken—emerged from the wreckage, ready to fight.
The Second Legion's fighters peeled off, engaging daemon-forged aircraft over decaying hangars. Dogfights lit the sky. Laser beams lanced across factory spires, while Thunderhawks and Stormtalons weaved through the polluted skyline.
And then—Doom himself descended.
The Doom Slayer, ancient warlord of terror, dropped directly into the maelstrom, smashing into the enemy's forward lines like a falling god.
At the designated impact zone, the Blood Angels arrived in full fury. Their drop pods fell like meteors, smashing heretic formations.
The ground quaked. The ruined city howled.
Gunfire. Roars. Screams. The war cry of the Imperium clashed with the unending cacophony of corrupted machinery and gibbering horrors.
Doom's Slayers and the Blood Angels fought side by side—black-green and crimson ceramite tearing through enemy lines. Together, they held the zone, carving out a beachhead for incoming reinforcements.
Then they surged forward—toward the heart of the corruption: the Purifier Factory.
Elsewhere across Vigilus, similar assaults unfolded.
Fighter craft skimmed low over shifting terrain, strafing targets with relentless fury. The Ultramarines, clad in cobalt plate, advanced through blasted ruins alongside the armored might of Rust-pattern tanks, their advance carving a path through toxin-choked streets.
In the southern sector, the Dark Angels executed a teleportation strike into a critical factory. Clad in Terminator armor, they obliterated the enemy command center in minutes.
But Doom's target—Dottolia—was another matter entirely.
It was the locus of corruption. Towering forge-complexes and warped fortresses loomed like sentinels. Massive spires of biomechanical steel formed hellish silhouettes against the toxic sky. And at their center...
A monolith of blackstone—twisted into the shape of a crown reaching for the heavens.
It pulsed with warp energy.
The techmarines of the Second Legion warned: this structure reversed Vigilus's magnetic poles, warping reality itself.
Doom and his brothers shared a grim understanding.
This "Blackstone Daemon Crown" was likely the true objective of the Chaos invasion. All the carnage, all the blood—just misdirection for something far worse.
They would not allow it.
Not while the Slayers still drew breath.
If their suspicions were correct, then these blackstone constructs were the most strategically valuable targets on the planet—each a node of unknown power, potential artifacts of ancient xenos origin, or worse, heretical tools tied to the warp.
With a cadre of honored heroes from his Chapter, Doom led over half of the Slayers' total strength in a direct charge toward the Blackrock Crown, a corrupted manufactorum believed to house these artifacts.
This declaration of war etched itself into the Imperial war map through noospheric channels, the signal relayed by the Imperium's vast data-net and picked up almost instantly across the sector.
Drop-pods and Thunderhawks rained from the skies. Thousands of Imperial soldiers—Guardsmen, Skitarii, and Astartes alike—deployed in waves, reinforcing the strike force.
Even commanders from distant war zones were stirred. Azrael, Commander Dante, and Calgar all arrived in succession, disembarking from Stormravens with their honor guards. The Dark Angels, Blood Angels, and Ultramarines each launched diversionary operations in other sectors of Vigilus to split the enemy's attention.
Faced with the full fury of the Imperium, defenders surged from every hatch and hallway of Dattoria. Word Bearers, their mouths spewing profane scripture, marched with twisted daemon-engines. They were followed by throngs of lobotomized slave-soldiers and corrupted Mechanicus constructs.
Among them came the Order of the Dead and Purifier Astartes, who utilized the hellish terrain of Dattoria's factories to mount a brutal defense. Between toxic chimneys, grenade launchers barked and plasma fire screamed like dragons in flight.
This was chaos incarnate. Only Primaris Space Marines—physically unyielding and mentally disciplined—could remain rational amid such bedlam.
Yet Doom pressed forward, his warriors driving east from the northern edge of the city. Warp-ghosts flickered across the visual displays of their helms, and machine-spirits faltered under waves of scrapcode and daemon-babble. Still, the Doom Slayers advanced without hesitation.
Each brother knew his role, communicating through reinforced vox-throats and combat-sign, their cohesion unshaken by madness or death.
This was familiar. Back when they had worn the flak and gas masks of the Krieg Death Korps, they'd charged through nightmares like this before. Then as now, they were disciplined, thorough, and pitiless.
They breached the outer manufactoria, tore down Purifier walls, and pushed into the industrial core. Bodies piled in their wake—thousands of foes falling to bolt, blade, and fury.
After a harrowing half hour in gas-choked ruins, Doom and his kin reached the heart of the complex.
But here, amidst a fog that clung like rot and steel structures drenched in chem-waste, they found something unexpected.
The Purifiers had constructed a seven-story spire using the corpses of the fallen, their twisted choir praising a single belief:
Life is the plague that infects the galaxy. Death is the cure.
Sacrifices burned on warp-tainted pyres. Here, Supreme Energy—the very source of power Doom had been seeking—pulsed with blasphemous light.
At its center stood seven blackstone crowns, amplifying the energies pouring into the altar. Compared to the sick ritual underway, these relics now seemed secondary. The true danger had arrived.
Doom inhaled deeply. He was about to give the order to attack when the ritual climaxed.
From the shadowed void came a terrible convergence—rot, spirit, and ruin merging into one towering presence.
The Daemon Primarch Mortarion had come.
Doom watched the Lord of Death ascend into the air before diving toward them, scythe in hand.
He had seen Mortarion before—in the putrid groves of Nurgle's Garden, where this traitor son had cleaved open the Garden of Fertility itself with that same rusted blade.
Yet Doom's spirit did not falter. How could it? Their father, Lion El'Jonson, was the embodiment of courage itself. These warriors had never known fear—not since they took the black soil of Krieg beneath their boots and looked toward the stars.
And so, even before orders could be given, Doom's brothers charged the abomination.
It was madness.
No Astartes, no matter how mighty, was meant to face a Daemon Primarch in direct melee.
Doom reached instinctively for something he hadn't used in decades—a military whistle, tucked deep in his utility pouch.
He ripped it free and raised it to his vox-grille.
"Fall back! Retreat! Don't you bastards dare charge!"
The piercing shriek cut through the vox-net.
In that moment, something ancient returned to him—a memory of when he had been a mortal Commissar of Krieg, ordering men to die not for glory, but for purpose.
That same unyielding valor still flowed in his blood. And though he wore Astartes armor now, the man inside had never truly changed.
Even in retreat, they marched toward death—not blindly, but with purpose.
To the enemy, it looked like panic. The Pestilence Warband believed the Imperials had broken at the sight of Mortarion, and rushed to pursue.
They had taken the bait.
However, Dukel had not expected that the moment the order to pursue was given, the Plague Army would collide head-on with the Doom Slayer.
The collective will of the Doom Slayers surged into an unstoppable tide of ceramite and fury, slamming into the unprepared ranks of Nurgle's forces like a sledgehammer into rotting wood.
It was not a battle—it was an execution.
The corrupted Astartes of the Purifiers, unenhanced by the Primaris ascension, were butchered like cattle. Their bodies, torn and broken, were soon strewn across the blighted ground.
The commanders of the Purifier host stood frozen, stunned by the sheer audacity and ferocity of the charge.
"…Lunatics," one of them finally muttered, grinding his teeth as the realization sank in.
Their front lines collapsed. Forced to retreat, the World Purification Army was driven back over the corpses of their fallen, pursued relentlessly by the Doom Slayers.
To slow the Imperial onslaught, the Purifiers' highest strategists—their own twisted Magos and plague-ridden psykers—remained behind, enacting a desperate rearguard action. They knew there would be no survival.
The bulk of the Purifier host fell back into a massive Gothic bastion embedded deep within the heart of Dattoria. Blood pooled in its dark corridors. Their numbers were shattered. Countless Purifiers and warp-twisted Librarians had been cut down. Even their commander—an Arch-Purifier—had been grievously wounded. Doom's mindblade had pierced through his corrupted armor, the red flame of anti-warp energy devouring flesh and spirit alike. His breathing was shallow. His agony, unending.
But hatred endured.
Through the shattered arch of a stained glass window, the Purifier commander stared down at the approaching torrent of Imperial might.
A flicker of cruel satisfaction lit his dying eyes.
Fools… they've overextended. Now they're surrounded.
He could see it clearly—the Doom Slayers, though successful in their charge, had pushed too deep, too fast. The enemy had closed in behind them.
And Mortarion… Mortarion was coming.
This time, he believed, there would be no miracle. Only death.
And the Emperor's angels would die screaming.
As the Doom Slayers advanced, battle-scarred and resolute, a monstrous figure emerged from the fog.
Twice the height of an Astartes, robed in corrosion and pestilence, he moved with deceptive calm—like a reaper striding into a field of ripe wheat. In his hand, the legendary Manreaper scythe glinted with the essence of death.
The Lord of Death, Mortarion, had arrived.
But still, there was no fear in Doom's eyes—or in the eyes of his battle-brothers.
Long ago, when Doom was but a mortal commissar in the Death Korps of Krieg, his finest campaign had ended with over a thousand dead guardsmen… traded for the death of a Greater Daemon.
A worthwhile sacrifice.
Thank you, Lord of Destruction, for the memory, he thought coldly.
Now, perhaps, fewer lives would be needed to bring down a Daemon Primarch.
Doom stared into Mortarion's rotting gaze with an indifference colder than the grave.