Dozens of Warp-portals, scattered across the territories of the various clans, stood primed and ready. The largest of these resided within the abyssal pits of the Clan Skryre warrens. Doomrockets, massive, obsidian-hued canisters forged from jagged cast iron and pulsing with a baleful green luminescence, were dragged forward by trembling lines of slave rats.
The Clanrats glanced about with twitching, paranoid eyes, terrified of being caught in the wake of these horrific ultimate inventions.
Accompanied by the dirges of Grey Seers, who brandished staves and shrieked liturgies to the Great Horned Rat, the Warlock-Engineers set to work. Clad in power armor fed by a constant hiss of warp-stone solution, they adjusted delicate components with bizarre tools, tapping at the metal wheels with manic precision.
"Yes-yes! Faster, quick-fast! The Great Horned Rat has no patience! If we fail... we, no-no, you, will suffer! Yes, I promise!"
Grey Seers, draped in filthy, ornate robes, shook their heads, adorned with multiple pairs of mismatched goat-like horns, as they spat threats to quicken the pace.
"Yes, we move! Moving-acting now!"
Finally, the calibrations were complete. The gargantuan metal wheels, braced by a chaotic scaffolding of iron and timber, looked like a blasphemous marriage of primitive carpentry and dark science.
Deep within the abyss, Ikit Claw sniffed the air, savoring the acrid aroma of warp-stone. With a sharp exhale, he slammed his claw down onto the activator.
Instantly, cables as thick and tangled as a knot of rat tails surged with the chaotic energy of the Warp. The power flooded into the metal rings.
BOOM-BOOM-BOOM—CRACK—HISS!!
The mechanical components shrieked, rattling as if they might disintegrate at any moment, causing the guarding Stormvermin to pull their heads into their collars.
Then, the cacophony smoothed into a low, vibrating hum. Arcs of green lightning began to swirl and spit between the metal rings until a translucent curtain of emerald light stabilized.
"YES-YES! Success-success! Charge in! Take-bring the Doomrockets through!"
Ikit erupted into a manic cackle, shrieking his commands. The Skryre legions, poised for the signal, began to pour into the shimmering maw of the portal.
Across the Under-Empire, other clan portals received the signal and were ignited by their respective Warlocks.
Thousands of Death Globe riders gunned their engines, their single-wheeled iron contraptions accelerating to a breakneck blur as their retractable blades extended. Behind them came the massive Doom-Wheels, rolling forward with the crackling power of warp-lightning.
From the depths emerged a black tide: swarms of vermin the size of hounds or calves, carrying the stench of rot and plague. They surged forward with a cacophony of chattering screeches, followed by a vast sea of Slave Rats, Clanrats, and the disciplined ranks of the Stormvermin.
Behind this initial wave, the bio-augmented rat-men of the Clan Resilience, a vassal of the Grey Seer clans, stood their ground. Their task was to protect the Seers and propagate the image of the Great Horned Rat as the Dark God of Technology.
In an instant, the Mid and Upper Hives of Bard exploded into a nightmare of vermin.
Horrific swarms erupted from every sewer grate, lightless alleyway, and shadow. They dragged down screaming civilians, gnawing them to the bone in seconds. They flooded warehouses, devouring grain, machinery, and power conduits alike.
Nothing survived in their wake. The resulting explosions, fires, and infrastructure collapses lit up the tactical displays of Bard Hive with a thousand points of distress.
Only then did the Astra Militarum and the Adeptus Astartes react.
The Guardsmen scrambled to lock down the thoroughfares. Heavy bolters and flamers were used to establish "death zones," cordoning off infested sectors with walls of fire. Those already covered in biting vermin were purged without mercy.
BANG-BANG-BANG—CRACK!
As the Astra Militarum fought to suppress the swarm, a volley of violet glass canisters fell from the heights in a high arc.
Unsure of the threat, several marksmen among the star-striding infantry raised their lasguns and fired. The fragile glass shattered instantly, releasing hundreds of thumb-sized pellets that spewed thick violet haze as they tumbled into the Imperial lines.
"Gas! Masks on, now!"
An experienced Commissar bellowed the order, and the rank-and-file scrambled for their respirators. But for many, it was too late. Those who inhaled even a trace of the violet vapor collapsed, their flesh liquefying as they bled from every orifice.
Even those who donned their masks were not spared. The gas was a corrosive, transdermal toxin; it ate through exposed skin and saturated fatigues, turning the soldiers' own uniforms into lethal shrouds. Within moments, men were reduced to puddles of melted bone and gore.
Hidden in the gloom, Avalanche Poison Wind Mortar teams worked feverishly, their power-exoskeletons allowing them to reload with tireless speed. These improved weapons, capable of devastating area saturation, were the exclusive, jealously guarded patent of Clan Skryre.
Following the toxic barrage, the Doom-Wheels and Death-Flayers tore through the streets with a terrifying industrial roar. The complex terrain of the Hive, which hindered the deployment of Leman Russ or Baneblade tanks, proved no obstacle for the skaven war-machines.
After all, compared to the lightless, vertical labyrinths of the Under-Empire, a human Hive City was as open as a highway.
With the Imperial forces reeling from the blitzkrieg, elite detachments of Stormvermin, Stormfiends, and Ghoritch-pattern Rat Ogres escorted massive iron "coffins" toward pre-designated coordinates.
The Adeptus Astartes finally counter-attacked. Thunderhawks and Land Speeders roared through the spires, racing to reinforce the most critical sectors.
A group of vengeful warriors plummeted from a gunship. At their head was a titan of a man in green armor, significantly larger than his brothers, wielding the Lion's Sword and the shimmering Emperor's Shield. Lion El'Jonson and his Dark Angels waded into the fray with righteous fury.
Every sweep of the Lion's blade saw dozens of rat-men cleaved in twain. The Primarch's heart burned with regret for his oversight, and he fought like a god of war to rectify it. He could see the reality of the battlefield shifting, aligning ever closer with the catastrophic end he had seen in his visions.
The Unforgiven, shamed by their failure to secure the warrens, fought with a desperate, suicidal ferocity. They smashed through the Clanrat lines, which had attempted to hold with trenches and warp-rifles, and drove straight for the enemy's rear.
Suddenly, a massive shadow plummeted from the rafters. A green-glowing blade hissed through the air toward the Primarch.
The Lion raised the Emperor's Shield, the impact ringing out like a cathedral bell. Only then did he see the true face of his assailant: a six-meter-tall monstrosity with digitigrade legs, a lean, muscular frame, and multiple pairs of twisted goat-horns. It was draped in a cloak woven of living shadows.
"You court death, daemon!" the Lion roared, leveling his blade at the beast.
"Strong-mighty ones are monuments for an assassin. And your head... is exquisite-captivating." Nightlord Sneek, the Master of Clan Eshin and the pinnacle of the assassin's craft, adjusted his neck with a sickening crack. He crouched low, the Weeping Blades in his hands longer than a man's claymore. His entire being felt like a cold edge drawn from the night itself.
Nightlord Sneek knew nothing of Primarchs. Even if he had, he would not have cared. No assassin fears a target for its strength; to him, this was merely another mark to be ended.
"You shall regret this!" the Lion bellowed as he charged. Nightlord Sneek leaped high into the air, a shadow descending to meet the sun.