The year M31.004 hung like a shroud over the Sol System. Beneath the artificial suns of the orbital plates and the serene-yet-vigilant gaze of the Emperor's Palace on Terra, the air was thick with unspoken tension. The grand design frayed at the edges; alliances whispered of strain, and the loyalty of sons was becoming a matter of grave, silent speculation. War was not yet declared in the open, but the foundation stones of the Imperium were grinding against each other, emitting sparks that promised inferno.
And then, there was Luna. Terra's ancient, pockmarked companion, transformed over millennia into a fortress world unlike any other. Its surface was honeycombed with void-shielded cities, its orbital space a lattice of weapons platforms, shipyard complexes, and defensive stations. It was the shield of Terra, the first and last line of cosmic defense. Impenetrable. Unbreakable. A monument to Human ingenuity and martial might.
High above, in a location that was less a place and more an architectural obscenity woven from stolen light and discordant geometry, Hisoka watched.
He wasn't a general, or a politician, or even a warrior in the conventional sense. He was an artist of anarchy, a conductor of catastrophe. His smile—permanent, painted in the soul—widened as he monitored the data streams. The symphony was reaching its crescendo. The Great Joke was about to land.
For months, he had tended his garden of discord: whispers sown in the ears of Primarchs, minor irritations amplified into interstellar incidents, the subtle redirection of resource flows, the gentle nudging of pride toward fatal arrogance. The Chaos Gods were clumsy, blunt instruments. Hisoka preferred finesse—the slow, agonizing build-up before the punchline.
His gaze drifted to a specific, humming node of energy within his warped domain. A beacon. Not of his creation—no, but one he had found—dormant, ancient, buried deep within the void. He had merely cleaned it up. Given it a little polish. And activated it.
The void rupture above Luna was not the stately, calculated arrival of a conventional fleet. It was a tear, ragged and screaming, like reality itself was being ripped open by cosmic claws. From the rent poured them.
The Shadow in the Warp hit Luna like a silent, psychic hammer blow. Communications flickered and died across the fortress world, the finely tuned NOCTE network of the Mechanicus stuttered, minds went blank or were flooded with primal, alien terror. It was the psychic scream of a thousand billion hungry mouths, focused into a single, annihilating frequency.
Hive Fleet Leviathan.
Not years away, as the Ordo Xenos had predicted. Not approaching along predictable tendrils of consumption.
Here. Now. Drawn by the beacon's unique pulse.
Not merely toward biomass—but toward meaning.
Panic erupted on Luna. Void shields flared, macrosystems powered up, fleet elements scrambled. But it was already too late for conventional defense. The first waves were not ships, but gargantuan bio-organisms—asteroid-sized spore cysts that hammered into the void shields like meteors, cracking and overloading them with sheer, chitinous force. The mass arriving was unprecedented. Obscene.
Hisoka chuckled, a dry, sibilant sound in his impossible chamber.
"See? The Emperor's shield. So strong. So proud."
He gestured with a languid hand toward the holographic display showing Luna being engulfed.
"Let's see how well ceramite and void shields hold against... instinct."
But this was not a simple, unthinking invasion. That would be too brutish, too blunt—far beneath Hisoka's twisted artistry. The beacon continued to pulse, but its output was subtly shifting. It wasn't just screaming FOOD! into the void. It was singing. A siren song. A melody of psychic resonance that spoke of ingestion, not just of flesh and bone, but of pathways. Of bypassing obstacles. Of subversion.
He was guiding them. Like a shepherd leading his flock to slaughter—except the flock was a galactic plague, and the slaughter was of everything else. He twisted their collective consciousness, nudging the myriad Norn-Queens and synapse creatures toward a singular, unlikely goal. Not just the surface biomass. Not just the juicy technological core. But something beneath.
Something forgotten.
The siege was brutal, short, and utterly tragic. Luna's defenders—the proud Legio Cybernetica, the Skitarii Legions, the Lunar Breachers of the Imperial Army, the handful of Custodes assigned to strategic key points—fought with desperate, heroic courage.
But courage meant nothing to the swarm.
Bio-acid rained from the sky, melting through hardened ferrocrete and vaporizing flesh. Gargantuan Hierophants strode over collapsed void shield generators, unleashing storms of living ammunition. Hormagaunts and Termagants poured from spore pods by the billion, a chittering, unstoppable tide that drowned everything in its path. Warrior-Broods adapted in real-time, chitin thickening against lasfire, bio-cannons mutating into plasma analogues, corrosive bile, and viral toxins.
The silence of the Shadow in the Warp was punctuated only by the alien screeches of the swarm and the brief, choked screams of the dying. Luna's miracles of architecture and defense became twisted, consumed landscapes. Towering manufactoria were stripped to their skeletons by voracious Rippers. Defense bunkers became tombs, their heavy doors ripped open, their occupants dissolved in acid or torn limb from limb.
But the main thrust of the swarm wasn't general. It was specific. Directed. Orchestrated.
They flowed like rivers of chitin through the ruins, converging on ancient shafts, forgotten sublevels, things hidden even from the Mechanicus' datavaults. Substructures rumored to predate even the Age of Strife. Linked by an echo in the warp, a psychic hum that only Hisoka—and now the Hive Mind—could hear.
Down into the moon's core they went, burrowing with seismic shockwaves and acidic vomit. The defenders couldn't understand. Why bypass strategic targets? Why ignore upper-level garrisons in favor of downward assault?
Because Luna hid a secret. A secret the Emperor had locked away.
A Webway Gate.
Stable. Ancient. Secure.
A path into the arterial network of the Eldar's broken empire. A backdoor to every corner of the galaxy.
As Luna burned, its surface becoming a slick wasteland of chitin and viscera, the Tyranids breached the chamber—a vast space lined with psychoreactive alloys, and in its center, a swirling vortex of iridescent, shifting light.
The Webway Gate pulsed in resonance with the beacon. And the Hive Mind felt it. Not just another planet. Not just another battle. This was a path. A way around the stars. Through the cracks of reality. An open buffet.
They didn't hesitate.
Genestealers, Lictors, Brood Lords, and endless waves of Gaunts poured into the Webway. The Shadow in the Warp over Luna thinned—its attention shifting into that ancient labyrinth.
Luna wasn't just conquered. It had been used.
The beacon fell silent. Its final signal: a perfect laugh. Mocking. Victorious.
On Terra, seismographs noted the shifts deep within Luna. Astropaths screamed and tore at their eyes as the Shadow twisted, no longer a shroud, but a web—stretching across the galaxy through impossible tunnels.
The news broke through the psychic veil. Luna had not fallen to Traitor Astartes. Nor to Orks. Nor to rebellion.
It had fallen to something alien, guided by something worse.
Hisoka leaned back in his impossible chair, feet resting on a console now blank of resistance. The transmission was over. Luna, that precious bastion of safety, was now a joke. A punchline. A spear. A burning thorn in the Imperium's most sacred place.
Was it operatic? Yes. Brutal? Absolutely. Tragic? Indisputably.
But most of all—it was ironic.
The overture of the Horus Heresy had begun.
Yes, Horus would turn.
Yes, the Legions would burn.
But long before brother struck brother... Leviathan was already inside the house.
All thanks to a jester who laughed at the very concept of fate.
The Great Joke had landed.
And now the galaxy was the punchline.