Mortarion unfurled his decaying wings and ascended through the choking mist, perching atop a crumbling Gothic spire. From this vantage, the Daemon Primarch of the Death Guard gazed down a spiral staircase into the war-torn remains of the city-factory below.
His bloated frame exuded a toxic miasma—an unnatural fog carrying death and despair—as he searched for Doom Commander Dukel, concealed somewhere behind a shattered bunker.
"Son of Dukel... what a shame. You will die here."
The Lord of Death's rasping whisper drifted through the fog—until a thunderous battle cry from the heavens shattered the silence:
"For the Lord Commander! For the Emperor!"
Thunderhawks screamed overhead, delivering Commander Marneus Calgar and his Honor Guard to the battlefield. Their ceramite boots struck the scorched earth with purpose, forming a resolute wall between Mortarion and his prey.
They were not alone.
Dukel's vanguard—the Doom Slayers—had torn open a brutal corridor through the heretic ranks, allowing the Imperial forces to breach deep into the corrupted manufactorum at the heart of Vigilus.
Azure-armored warriors surged forward. The moment they entered the kill-zone, they unleashed a withering hail of bolter fire at the Daemon Primarch from all angles.
From a rent wall emerged a dozen Redemptor Dreadnoughts, their heavy flamestorm cannons igniting the mist in brilliant waves of fire. The sheer fury of their assault echoed with vengeance; Mortarion's defilement of the Five Hundred Worlds during the Plague Wars had never been forgotten.
The Ultramarines had returned—not just as defenders of Imperium Nihilus—but as avengers of the fallen.
But Calgar's wrath was tempered by experience. The brutal counter-assault from the Purifiers had bought him the precious seconds needed to orchestrate a proper encirclement. Layered firing lanes, overlapping kill-zones—everything was calculated. Even Mortarion, avatar of disease and entropy, found himself hard-pressed to break free.
Dukel—Doom Commander of the Slayers—fought like a war-god incarnate, carving a bloody path through swarms of heretics. Each Chaos cultist who barred his path fell beneath his wrath.
No warrior here, save him, stood a chance of facing the Daemon Primarch and surviving. And he would not allow his brothers to die under Mortarion's rotted scythe.
He accepted the burden of this confrontation without hesitation.
Above, the skies had transformed into a furnace of war. Valkyries, Thunderhawks, and Blight Drones clashed amidst contrails and flak bursts, while below, the ground trembled from bolter fire and chainblade duels.
Blood stained Dukel's armor. Around him, his Doom Slayers were red from helm to boot. With every step, their heavy boots crushed bones, each crunch a solemn requiem for the fallen.
Dukel ascended a slope of shattered corpses and broken metal, stepping onto a ruined platform that once bore the manufactorum's warning fence. Poisonous chemical runoff puddled around rusting pipes, while unholy runes writhed on the corroded surfaces of daemon-haunted machinery.
He pressed on.
At a breach in the wall, Dukel halted briefly. His crimson lenses surveyed the massacre below.
To the north, Commander Dante and his Sanguinary Guard had struck like angels of death, surrounding plague zombies and death cultists near a toxic smokestack. The Sons of Sanguinius moved like wraiths—elegant, swift, and merciless.
To the northeast, Dark Angels armored columns clashed with chanting Word Bearers, trading volleys of plasma and infernal sorcery. Daemon engines and heretical war-constructs stalked the ruins, facing off against relics of the Great Crusade and innovations from the Fabricator-General's forge worlds.
Before Dukel, the bulk of the Ultramarines were locked in savage melee with plague-ridden Death Guard. Azure armor was smeared with bile, ichor, and blood.
Then Dukel looked up—to the top of the spire.
The Ultramarines Honor Guard were engaged in a desperate duel with Mortarion himself.
The battle had now reached the factory's periphery. The outer walls collapsed under the strain of conflict; bricks and ferrocrete rained like hail from the crumbling tower.
Through the exposed colonnades and broken halls, the battlefield revealed itself in full horror. The ground was carpeted with the corpses of Ultramarines and Death Guard alike. Dukel's enhanced vision caught every detail—the rents in power armor, the lifeless gazes of fallen heroes, the silent testimony of sacrifice.
Some bodies had slipped into acidic runoff. Their ceramite was half-dissolved, their limbs mangled and floating in industrial vats like grotesque relics.
One Redemptor Dreadnought, emblazoned with the Aquila, had fallen in glorious defiance. Its pilot, mortally wounded, had initiated self-detonation. The explosion tore through multiple levels of the tower, sending burning wreckage crashing down like a dying angel cast from heaven.
Blood painted every surface. Each wall bore handprints and sprays of gore—silent echoes of resistance.
Even Mortarion had not escaped unscathed. His tattered armor smoked, scorched by promethium. The fiery onslaught ignited the very toxins he carried, wreathing him in a shroud of smoke and fire.
Yet even encircled, the Daemon Primarch was death incarnate. His reaper's scythe—Silence—mowed through the finest warriors of Macragge as if they were children before a god.
The Doom Slayer charged again.
His pace was relentless.
Ahead, he saw Mortarion decapitate the banner bearer of the Glory Guard with a single, contemptuous swing. The corpse was cast from the spire's heights, tumbling through smoke and ruin, crimson blood painting the banner it once upheld.
Dukel's fury erupted.
So many had died for him to have this chance. The Ultramarines, the Blood Angels, the Dark Angels, even the Doom Slayers—they had all bled to deliver him here.
He would not let their sacrifice be in vain.
He could not stand by and watch his brothers die in his place.
In a desperate move, Doom twisted the mind-hub of his double-barreled Argentum shotgun. His Argent backpack trembled as he took aim and fired directly at Mortarion, the Death Lord.
The Doom Slayers required no command. Acting on instinct and shared discipline, they too twisted their mind-hubs. With synchronized precision, they unleashed a barrage of blazing red Argentum-energy rounds.
Like a thousand-headed serpent of fire, the storm of rounds surged toward the Daemon Primarch. Even at a distance, their shots struck true.
Mortarion, engulfed in red flame, let out his first true roar since descending upon Vigilus.
The warheads were no ordinary rounds—they had been specially forged under the Fabricator General's guidance. Reinforced and infused with sanctified energy, they tore at Mortarion's daemonic form, disrupting even his essence in the Immaterium. His corrupted armor shattered in wide swathes, and the energizing warheads of the shotgun punched through his physical form.
Scarlet flame surged from his wounds, defying even the noxious miasma that clung to him like a second skin.
No blood spilled—only thick, caustic smoke poured out, rising like incense from a burning offering. The pain was undeniable. The Lord of Death abandoned his slaughter of the Glory Guards, turning his full fury upon the Doom Slayer charging toward him.
Doom was closing the gap—less than a thousand meters now. For him, a dozen seconds at most.
But before he could close the distance, a blur of cobalt and gold surged up from the shattered lower levels. Astartes armor gleamed, and a power sword crackling with a force field cut through the air, aiming straight for Mortarion's corrupted heart.
"Calgar, beware!" Doom roared.
He recognized the warrior instantly—Chapter Master Marneus Calgar of the Ultramarines. Reckless or righteous, he had thrown himself into the lion's jaws.
Doom pulled the trigger, laying down suppressive fire to cover the strike.
Mortarion reacted with unnatural speed. He twisted mid-air, avoiding the Slayer's barrage. With a grim hiss, he brought down Silence—his massive scythe—to intercept Calgar's blow.
Steel clashed with warp-wrought metal. The shockwave rocked the factory. Mortarion was driven back a step. Calgar, however, was hurled dozens of meters through the air, crashing into the reinforced grille plating. Steel bent inward beneath his impact.
He did not rise.
Mortarion's pale lips twisted into a cruel grin as he loomed over the fallen Chapter Master.
Doom clenched his teeth.
Calgar—noble, proud Calgar—lay vulnerable at the Daemon Primarch's feet. And he, the Doom Slayer, was still too far to intervene.
A few hundred meters had never felt so far. In this moment, it might as well have been the void itself.
The scythe rose high. Mortarion prepared to strike the killing blow.
Then the world changed.
Without warning, crimson fire erupted amid the smog—impossible, sacred fire. It crackled and burned with purpose, tearing through the pestilent mists like divine judgment.
From within that sea of flame, a figure emerged.
The flames parted, revealing a massive warrior wreathed in fire, his blood-red cloak billowing like a banner soaked in martyr's blood. At his back came chanting—sacred hymns carried by the voices of Battle Sisters, forming a solemn ring around him as if drawn by faith itself.
But none looked at the Sisters. All eyes turned to the one who stood before Mortarion.
Doom stared, his breath caught. He didn't need logic—his gene-seed sang the truth.
Every Astartes present knelt.
Because this was Dukel.
The Imperial Warmaster, their Primarch, the Scion of the Lion, the one whose gene-forge birthed them.
At the edge of death, he had arrived—not as a savior of one, but as the shield of all.
Doom's heart swelled with reverence—and with guilt.
He had sworn to hold Vigilus. He had promised the Primarch that he would end the threat. Three Legions had been entrusted to him. Heroes beyond count had followed his call.
And yet—this.
The fall of the Vigilus System. The destruction of its spires. The Blackstone Crest's collapse. Abaddon's escape. The lives the Ultramarines sacrificed in their stead.
He clenched his fists. His failure was laid bare in the shadow of his gene-father's presence.
Mortarion paused. His scythe lowered—but only slightly.
The Daemon Primarch's eyes narrowed.
He stepped back, abandoning Calgar, studying Dukel with reptilian wariness. He recognized his brother. But was this truly him?
No words were exchanged. They had no need for them. There was no warmth between these two sons of the Emperor—only the cold calculus of warriors who had long passed the point of reconciliation.
Both knew what came next.
Mortarion struck first.
He had no choice. As the challenger, he had to seize the initiative, disrupt the Warmaster's rhythm. His corrupted wings flared, and he surged forward, Silence raised high.
Dukel met him head-on.
The blade of fire and the blade of rot collided.
Steel shrieked. Sparks flew.
And the battle between Primarchs shook the world once more.
The blade of Mortarion's scythe swept in at a wicked angle—but was casually deflected by Dukel with a single armored punch.
At the moment of impact, the sickle collided with the iron gauntlet and was repelled by a concussive burst of red flame. The force was so tremendous that Mortarion, massive even among the Primarchs, staggered backward.
Seizing the brief opening, the spiritual battle-sisters at Dukel's side launched a coordinated assault, striking in unison. Their movements were graceful yet unnatural, imbued with otherworldly precision. Mortarion's eyes narrowed. He hadn't realized how closely these sisters resembled the Doom Slayers—not merely in discipline, but in power.
With a violent sweep of Silence, his corrupted weapon, the Lord of Death retaliated. Though the sisters raised their wards in time, they were still hurled away by the sheer might of the blow.
"Stand down," Dukel commanded, his voice deep and resolute.
At once, the nuns obeyed, retreating into the cover of the crimson flame that danced unnaturally around him. Their sudden withdrawal was no sign of weakness—only that their Warmaster had claimed this battle for himself.
Like a territorial predator refusing to share its prey, Dukel stepped forward, eyes burning with purpose.
Mortarion took a cautious step back.
But the Warmaster was relentless.
Doom, watching from the ruined lower tier of the manufactorum, suspected Mortarion's retreat was no true flight. The Death Lord wasn't one to abandon a battlefield easily. Perhaps he intended to draw Dukel away—away from the fallen Calgar, who still lay broken at the Lord of Death's feet.
If so, Doom knew he couldn't wait.
He and the nearest Doom Slayer moved swiftly, lifting the battered form of Chapter Master Calgar. A quick auspex scan revealed a heartbeat—weak, but present. Doom exhaled, feeling a crushing weight lift from his chest.
Above them, the two demigods clashed atop the spire.
Mortarion unleashed a tempest of savage strikes, each blow infused with corruption and centuries of martial experience. But Dukel met them with fluid defiance. He did not simply block—he dominated, his flaming strikes turning aside the daemon weapon again and again.
Fire and pestilence clashed like gods at war. Black smoke hissed where red fire met toxic fog, the sky roiling with the struggle between purity and decay.
From below, the sharp report of grenade launchers echoed as Doom's attention was abruptly dragged back to his own war. Projectiles pinged off his ceramite armor, their impact a reminder that the battle was far from over.
"Doom," came the gravel-toned voice of Grand Master Azrael over vox-link, "The Plague Marines are breaching the steel support frame—your flank is in danger."
Only then did Doom realize how long he'd been transfixed by the duel above. Shame filled him. He'd been entranced by the arrival of the Gene-Father, forgetting that his own battle had yet to be won.
He rallied quickly, sprinting toward the breaking front lines. But even as he fought, his eyes kept rising to the tower.
Dukel was pressing Mortarion now, driving him back with a storm of blows. Each strike seemed forged from vengeance and fire, hammering down with enough force to rupture the armor of gods.
For the first time, Mortarion was on the defensive—his monstrous form shrinking beneath the fury of the Warmaster.
As they traded blows, Dukel glanced downward.
Their eyes met.
And in that fleeting instant, Doom felt as though the Primarch's gaze struck his very soul. It was not just a look—it was a command, an expectation. His gene-seed stirred with ancestral recognition.
He understood without a word.
A fire ignited in his blood.
Above, the red flames intensified. Mortarion had nowhere left to stand. With a final beat of his plague-ridden wings, he soared up and vanished into the festering green clouds above.
Dukel looked down at the battlefield one final time.
Then, like a meteor wrapped in fire, he launched into the sky after his brother, vanishing into the poison mist trailing fire in his wake.
The duel of demigods was no longer within mortal sight.
But their legacy remained.
Doom stood tall, lifting the Sword of Mind high above his head. The blade blazed with psychic fire.
"For Dukel!" he roared.
The flames surged outward like a supernova.
His cry echoed across the steel caverns of the ruined manufactorum—and all who heard it answered. Doom Slayers. Ultramarines. Dark Angels. Guardsmen. Magos. Every loyal servant of the Imperium raised their voice as one.
Their combined roar drowned out the thunder of artillery and the scream of bolters. It swept across the battlefield like a righteous tide, tearing through the veil of poison that had smothered Vigilus for far too long.
"For the Warmaster! For the Emperor!"