The Legion of the damned. Berserk x warhammer 30k crossover.

Location: A Hidden Vault Within Luna.

Luna was where mankind first touched the Cosmos. The first mark they left when they ascended from their cradle to explore the stars. It was only fitting it would be where mankind's ascension started. In shadows of the Old Night, the newly crowned Emperor of Mankind started a impossible project within Luna. Using his own genius and the resources of newly conquered Terra and Luna, He sought to create beings that would guide mankind along the Shining Path.

The results of this great endeavor were twenty artificial wombs, each containing a fetal transhuman greater than even anything crafted. Born of millennia of scientific discovery, warpcraft stolen from the Immaterium, and the very blood of the Anathema. These Primarchs were built to be the heroes of a new age. An age of Imperium, where Humanity was ascendant and no longer feared the darkness. A noble ambition, but other forces stood in opposition to the newly crowned Master of Mankind. The primordial warp Gods sought to claim these infant Primarchs. To warp them from paragons of mankind to tools of doom and darkness.

Reality shimmered as spacetime was distorted by a Warp Rift. The Ruinous Powers had gambled everything on this. An Immaterium born paradox that would seal both the Galaxy and the Anathemas Fate. Using sons of the XVII Legion and the insanity of warp currents, they planned to pluck the twenty Primarchs from safety and twist them however they pleased.

Argel Tal and his brothers of the Serrated Sun Chapter exited the rift. Stunned and disjointed by the flickering visions and movements through reality, Argel Tal attempted to identify his surroundings to no avail. The oily voice of Ingethel the Ascended poured into his mind. Secrets and lies were pumped into him like a serpent's venom. Like the puppets they were, the Word Bearers moved forward with a stiff halting gate not known to Astartes. With their faith in the Emperor shattered fully, and the Primordial Truth laid bare, Tal knew what must be done.

Moving slowly past the glass wombs he pulled forth his blade and advanced on the Gellar Field generator at the center of the chamber. The True Gods would save the Primarchs from the False Emperor and his Father would be vindicated. In his stupor, he lifted his blade and prepared to destroy the only defense the infant demi-gods had from the predators of the Warp.

Right as his blade began its downward arch, the warp stirred again. Ingethel let out a screech when she felt the power and its source. At the other end of the chamber from the Serrated Suns' portal, another gash in the Materium opened up. Not a gash that wept corruption and Chaos like the first, this one burnt with Holy Fire. Ingethel began to quake her Daemonic form weakening under the pressure coming from the rift.

"Anathema… THE ANATHEMA HAS COME!" the newly born Daemon Prince wailed in horror and fear as the aura of the being her kind feared above all burst forth from the portal.

The Word Bearers sensed it too, and as one their hackles raised at the False Emperor's presence. The pain and humiliation of Monarchia was a fresh wound in their Transhuman memories. Yet even the Word Bearers who had been witness to the Emperor's wrath were shocked by the energy leaking from the rift. While the power unleashed on Monarchia had been far more brutal and unrestrained than the usual psychic aura the Emperor gave off, this was far worse. It was a nova of sheer psychic dominion. Unfettered by mortal constraints, it bathed the chamber in a white light that seared the minds and souls of the Heretic Astartes.

Ingethel buckled under the scalding light, and her form was hurled screeching back into the Warp. With their portal collapsing and their guide gone, the Word Bearers were lost and confused. Their Pilgrimage of enlightenment had turned into a trap. The worse for them was yet to come though. For this warp rift was not meant to banish Ingethel or protect the infant Primarchs from Chaotic taint, but to transport a chosen few through time and space to avenge themselves and save the Imperium. The Legion of the Damned had come to change destiny.

Bolterfire erupted throughout the laboratory as the Damned open fire on the Word Bearers. Diving for cover, the Traitor Astartes were pinned down by constant volleys of burning ammunition. A number of them had been too late to react to the sudden appearance of ghostly burning Astartes and were now reduced to hunks of burning meat and bubbling blood. Recovering first, Tal ordered his Battle-Brothers to open Fire on the Phantoms while avoiding the infant Primarchs.

Bolt Shells whizzed past the Gestation Capsules as the firefight continued. Alarms and Klaxon began to wail adding to the frantic chaos. Slowly but surely the Legion of the Damned moved closer and closer to the embattled heretics. Peering behind his cover Argel Tal noticed the Number on the gestation capsule one of the Damned hid behind. XIII. Struck by grim inspiration he fired his Bolt Pistol at the Womb of what would be Guilliman. Attempting to kill two birds with one infernal shell.

Moving faster than what was thought possible for an Astartes, one of the Legionaries threw himself in front of the shell. It punctured the Ghostly Astartes armor and he flickered out of the materium like a candle snuffed out by the wind. Tal's transhuman eyes noticed something particular about the martyred enemy. His armor may be burnt and blackened, but the inverted Omega on his pauldron was still barely visible.

"Sons of Guilliman always willing to follow their arrogant father," he thought to himself before barking orders to his sons.

"Target the Capsules marked I, VI, VII, XI, XIII, XVIII, and XIX" he barked. Tal knew his purpose here was to allow the Gods to claim the Primarchs, but if he could not do that then at least he could cripple the False Emperor and eliminate threats to his father and his legion before they even existed. Or at the very least allow these phantoms to martyr themselves saving what might be their future gene-fathers.

Argal Tal's hypothesis was correct. Legionnaire after legionnaire stood in front of the incoming fire to protect the infant Primarchs. Yet even with these casualties, these blacked, flame ensorceled saviors still advanced on the Word Bearers, butchering the heretics with Bolt Fire and even their blades if they got close enough to a straggling one. What had been a slaughter became a pitched a battle between the rows of Gestation Capsules.

After ten minutes that seemed to last ten hours, only a handful of Damned Legionnaires along with Tal and his three remaining Serrated Suns. Word Bearer corpses and bolter shells littered the room, while the Chambers doors quaked with the attempts of outside Imperial Forces attempting to breach the sealed laboratory. Cursing in Colchisian, Tal barked orders to his remaining Battle Brothers. They were running out of time. Even if they won this battle, the False Emperor's slaves would kill them instead.

Ordering his Brothers to retreat, they charged towards the Gellar Field generator hoping to salvage their original objective. One Heretic stayed behind to provide covering fire. He screamed maddened Colchisian prayers as flaming bolter rounds tore him to pieces. The remaining three charged towards the generator as the Legion of the Damned pursued. A volley of flaming ammunition ripped apart another Word Bearer, but they were so close. Mere meters away from salvation and humanity's eyes being opened to the Primordial Truth.

His desperate hope would not come to pass however, for while the firefight raged, one last being exited the Legion of the Damned's portal. He now stood in between the last two Heretics and the Generator. Towering over both Astartes, with armor as burnt and blackened as the others, it was still unmistakably a Custodes. With a single slash of his burning Guardian spear, Tal's last remaining Brother was dead and he stood alone against a blackened burning ghost of the Emperor's foremost warriors.

For a split second, Argal Tal and the Custodes stared at each other. Tears of Molten Metal trickled from the Custodes visor as recognition dawned upon the Serrated Suns captain.

"Aquillon?" he wondered, fear and trepidation creeping into his voice. As soon as those fateful words of recognition left his mouth, the Guardian Spear of the Vengeful Custodes parted his head from his body.

A.N. The information on the periods of Imperial History is fairly inconsistent and spotty so there will be most likely errors in timelines and similar things. The basics of this story is it starts towards the end of the Unification Wars. Terra is almost fully conquered by the Thunder Warriors on their last legs and Luna is subjected fully. Mars has not been contacted and the Primarch project is almost finished. The Emperor protects!!!!!)