In an unremarkable star system within Segmentum Ultima lay the world of Keilia. As one of the Imperium's countless Agri-Worlds, Keilia was no grand capital, yet its harvests sustained the populations of dozens of neighboring systems.
Now, the world's endless, monotonous plains, shrouded in the toxic, chemically choked air of industrial farming, were unrecognizable. The defenders of the Imperium were locked in a desperate struggle against brainless horrors that swarmed like locusts from the void.
In orbit above, a splinter of Hive Fleet Kraken continuously disgorged biological mycetic spores, which rained down upon the surface like malignant seeds.
The mortal defenders could do little but endure. Fortresses and trench lines carved the ravaged earth into ugly, segmented fronts. Within plasteel bunkers, sandbagged emplacements housed Basilisks that thundered incessantly, while Hydra flak tanks fired madly into the sky, attempting to cull the swarms of Gargoyles that threatened to blot out the sun.
"Do not falter! Do not cease fire! Pour your souls into your triggers and cleanse these damnable xenos! The God-Emperor protects!"
A Commissar, greatcoat snapping in the wind and power sword held high, shrieked encouragement through the trenches. Guardsmen in forest-green flak armor and Aquila-stamped helmets gripped their lasguns with expressions of either grim resolve or blind terror, unleashing volleys of light.
Snap-crack-snap!
Crimson las-beams punched through swarms of Hormagaunts, cauterizing holes through the chitinous carapaces of the Tyranid chaff. But for every beast that fell, ten more surged forward. Interspersed among them were Termagants, their fleshborers, symbiotic organisms linked to their own nervous systems, spitting beetles suffused with caustic acid at the human lines.
When a Guardsman was hit, they let out bone-chilling screams as the flesh-boring beetles ate them alive from the inside out. In the grand calculus of this war, however, no one cared. The life of a single "Low Gothic" grunt was as expendable as a single gaunt.
But then, the fabric of reality tore. A Warp rift groaned open, and a fleet of ramshackle, "illegal-construction" style scrap-vessels, resembling a floating junkyard more than a navy, tumbled into the system.
Clan Moulder had arrived.
"Go-go! See what thing-things move there!?" Throt the Unclean barked, his three arms twitching. Guided by the Warp-navigation of a Grey Seer, he had materialized in this unfamiliar reach of space.
Through the flickering view-screens, he beheld the massive bio-ships orbiting the planet—monstrosities that looked like a blasphemous union of colossal beetles and ammonites, "shitting" out spores toward the surface.
Throt's beady rat-eyes ignited with greed.
This was exactly the "prime specimen" he had dreamt of! Back on Zavka, the other clans had hoarded the lion's share of Genestealer subjects, leaving Moulder with mere scraps. If he could secure such a vast quantity of biological material, Throt swore he would make Clan Moulder Great-Great Again!
Currently, the Moulder fleet was forced to rely on Skryre's "stolen" technology. Even his own Stormvermin bodyguards were equipped with Skryre-tech. It felt as though Moulder had become a mere lackey to the Warlock-Engineers. In this interstellar age, the Technological Clans held all the cards. No matter how strong a Rat Ogre was, a single blast of Warp-lightning could end it.
But gazing upon these cosmic monsters, Throt saw his path to resurgence. If they could crack and recode these xenos genes, the "rat-scum" of Skryre would no longer be fit to stand above them!
Of course, being a Skaven and therefore possessing a healthy, cowardly fear of death, Throt would never lead the charge himself. He promptly kicked one of his Stormvermin guards, snarling, "Why no scouts yet?! Stupid-fool!"
The Stormvermin squeaked, turned, and sprinted off to kick a Clanrat Chieftain, ordering the brown-furred wretch to prepare drop-pods and "suicide-scout" units immediately.
The command trickled down the hierarchy of misery until the "honor" finally fell upon a small, nameless thrall-clan.
"Quick-quick! Go! It is the will-command of Lord Throt! Yes-yes!"
A Moulder Stormvermin, standing nearly six feet tall, loomed over the minor Chieftain. He wore drab, dun-colored power armor, powered by a ramshackle back-mounted generator hiss-dripping with Warpstone fluid through green tubes. Clutching a triangular tower-shield and a power-cowl, he looked formidable.
The Chieftain of the "Fang-Grip" Clan looked upon the elite guard with a mix of despair and avarice. Despair, because he knew his kin were being used as fodder; avarice, because even the Chieftain lacked the quality gear the Stormvermin wore. His own armor was merely shards of non-powered ceramite lashed together.
Throt, a master of the "carrot and stick" method, had authorized the Stormvermin to dangle a bribe: "Lord Throt says... if you succeed-win, you get breeders! Many-many female-rats! And first-pick of the Lord's new experiment-things!"
It was common knowledge that Throt the Unclean was the second-greatest Master Mutator in the clan. His "experiments" were coveted by every warlord in the Under-Empire. With such a prize, this tiny clan could swallow its rivals whole.
His heart hardened by greed, the Fang-Grip Chieftain nodded frantically. "YES-YES! Long live Lord Throt!"
From the hangar bays of the scrap-fleet, strange drop-pods equipped with massive drills at their base were launched. These pods ignored all Imperial specifications, their sizes varying wildly according to the whim of their creators. Driven by Warpstone-fire, they streaked toward the planet's surface, trailing noxious green flames.
Minutes later, with green retro-thrusters firing to mitigate the impact, the pods slammed into the earth and their drills began to scream. Tearing through rock and soil, thousands of pods buried themselves deep underground, unleashing an uncounted tide of vermin.
Indeed, when a Skaven deploys, they deploy an entire clan. These burrowing pods were designed to give the ratmen a fighting chance to infest and breed rapidly beneath the surface. Hundreds of thousands of Skaven took root. Once the breeders were secured, the Fang-Grip Chieftain ordered his warriors to push outward.
Because they had burrowed into a "no-man's land" where the Tyranid and Imperial forces were still locked in stalemate, the pods went unnoticed by the humans.
The Tyranids, however, noticed.
A group of Tyranid Warriors, leading a host of Gaunts tasked with reclaiming biomass, sensed the arrival of these celestial interlopers. Driven by the instinct to protect the cat-sized Rippers that were busy consuming the dead, the Warriors led tens of thousands of Gaunts toward the impact sites.
They arrived to find the earth riddled with a dense network of tunnels, most of which had already collapsed into a labyrinthine warren. The Tyranid Warriors commanded their lesser kin to dive into the dark to exterminate the unknown threat.
Seconds later, the synapse-link for those Gaunts winked out.
Then, from every shadow and crevice, came a sound, a dry, rustling scuttle-scuttle followed by a high-pitched chittering that would make any mortal's skin crawl.
"SQUEE-SQUEE-SQUEE-SQUEE!"
The noise swelled into a cacophony as millions of red eyes emerged from the soil. They were the size of Rippers, but these creatures were covered in filthy, matted fur, possessing razor-claws and yellowed fangs. From the gore staining their whiskers, it was clear the Tyranid scouts had not been killed—they had been eaten.
The Tyranid Warriors let out a psychic scream of fury.
In the history of the Great Devourer, it was always they who did the consuming. To be preyed upon by these weak, stinking creatures was a defiance the Hive Mind would not tolerate.
The Warriors flourished their bone-swords, letting out a terrifying roar as a carpet of Rippers and Gaunts surged forward to turn the vermin into biomass.
As the Tyranids charged, the rat-holes widened. From the darkness, ten thousand glowing green projectiles hissed through the air.
"FOR THE—YES-YES! FOR THE HORNED RAT!!"
Though not their first brush with Genestealers, this was the Skaven's first true engagement with the main host of a Hive Fleet. The War for the Biomass had begun.