Roboute Guilliman had no intention of pursuing the fleeing Abaddon. In the eyes of the Primarch, the Despoiler's significance paled in comparison to the fate of his own brother. The most pressing matter was locating the missing The Rock and the Wrath of Baal.
Returning to his private sanctum, Guilliman fell into a heavy silence as he gazed upon the towering icon of the Emperor. He rose and retrieved the flaming sword resting in the icon's hands.
"Vashtorr..."
Guilliman whispered the name to the blade.
Parsecs away, the Daemonic Demigod currently launching a brutal assault on The Rock felt an inexplicable shiver. Vashtorr probed the Warp for the source of this sudden unease but found nothing. He turned his focus back to the fortress-monastery. He had already set foot upon the outer bastions of the fortress, commanding a vast host of daemons, World Eaters warbands, and traitor auxiliaries.
Profane Daemon Engines, thrumming with the sickly resonance of the Warp, ground forward. Tides of Neverborn surged from the void. Towering Daemon Princes brandished colossal mauls, Heldrakes shrieked through the upper atmosphere of the asteroid-fortress, and Bloodthirsters lashed out with whips and hellblades.
"Blood for the Blood God! Skulls for the Skull Throne! Death to the lackeys of the False Emperor!"
The World Eaters bayed with ecstatic fury, revving chainaxes and firing bolters as they sprinted through the daemonic waves. These entities and Chaos warbands were not Vashtorr's direct vassals; they were bound by the "Soul-Forged" daemonic pacts he brokered. As the preeminent scientist-artisan of the Warp, Vashtorr supplied them with war engines and wargear, but his gifts were never free. Those who could not pay the price of his contracts found themselves indentured to the Arkifane for eternity.
Over ten millennia, the Tower of Angels had been reinforced and retrofitted countless times. It was more than a Chapter Monastery; it was a peerless super-fortress.
Searing plasma geysered from the monastery walls, incinerating the vanguard of the daemonic host. Autocannons and heavy bolters roared in a deafening chorus, weaving a curtain of lead interspersed with the azure streaks of plasma and the orange glare of multi-meltas. Nearby, the Wrath of Baal fought in close coordination with the remaining Dark Angels fleet, locked in a lethal dance with the Chaos armadas.
The arrival of the Blood Angels had truly exceeded Vashtorr's calculations.
The plan had initially unfolded perfectly. The planet Wyrmwood had acted as the bait, drawing the Dark Angels and eventually The Rock itself into the snare. An Ark of Omen waiting in ambush had been partially crippled by a hidden macro-cannon array on the asteroid, leading Vashtorr to realize that even an Ark struggled to match the sheer mass of The Rock.
Yet, just as he prepared to crush the fortress, the Wrath of Baal had arrived. The sudden manifestation of Lion El'Jonson had caused The Rock to abandon the crippled Ark and pursue the Blood Angels' flagship. Vashtorr had been forced to redirect a portion of his fleet to maintain the chase.
To Vashtorr, Wyrmwood was irrelevant. His goal was singular: the ancient relic buried deep within the heart of The Rock. The Tuchulcha Engine.
Vashtorr had already secured the Ouroboros. He had wrested the Plagueheart from the clutches of a Nurgle-aligned faction. Now, he only needed the Tuchulcha to construct the legendary Dissonance Engine, a key to the vaults of the Old Ones hidden deep within the Webway. The Arks of Omen had merely been a charade to manipulate Abaddon.
Vashtorr's dream was nothing less than his own ascension to godhood.
Within the monastery, the Dark Angels witnessed something unprecedented: a gathering of Watchers in the Dark. Dozens of the small, hooded figures, led by several clad in pristine white robes, stood together, brandishing psychic staves twice their height.
The Watchers did not speak; they communicated through direct psychic resonance. A violent empyrean storm churned above the monastery, thick with their anger and disdain. As the lead Watcher struck his staff against the floor, blinding pulses of blue-violet psychic energy erupted.
The waves of power washed over the approaching enemy, banishing thousands of daemons back to the Warp in a single heartbeat. No one knew the true origin of these mysterious beings. Even Grand Master Ezekiel, the Chapter's Chief Librarian, had never pierced the veil of their mystery. Records indicated they had appeared to the Emperor when He first met the Lion on Caliban.
Vashtorr watched the soaring psychic display with cold curiosity. He had never heard of the Dark Angels possessing such raw empyrean potential.
But while the daemons were banished, the traitors were not.
The World Eaters pushed forward with legions of twisted cultists, mutants, and Daemon Engines. The Black Legion followed in their wake, while the Iron Warriors provided armored cover and heavy fire support. Word Bearers and Thousand Sons began to chant, weaving counter-spells to neutralize the psychic storm.
Facing overwhelming numbers, Grand Master Belial of the Deathwing, Ezekiel, Interrogator-Chaplain Asmodai, and Supreme Grand Master Azrael directed the Dark Angels in a desperate defense.
The roar of siege engines intensified, and soon the outer curtain wall of the monastery was breached. A massive explosion threw Dark Angels and traitors alike through the air.
"Azrael! I request authorization to release the Excindio Battle-Automata!"
A figure in bone-white Terminator armor, swinging an obsidian greatsword, sheared through several frenzied cultists. As the blade moved, the very sound around it seemed to be devoured, leaving a hollow silence where the screams of the heretics had been.
"Belial, those horrific Abominable Intelligences could destroy the entire monastery!" Azrael shouted.
A hail of munitions sought him out, but an energy field deflected the fire. Clad in his ornate winged helm and the Protector's plate, Azrael decapitated a charging World Eater before drawing the Lion's Wrath, his combi-plasma, to slag an encroaching Daemon Engine.
The Deathwing ship Azrael's Second was locked in a void-duel with Vashtorr's fleet nearby. It housed the Excindio, terrifying silicon-based sapient machines, relics of the Dark Age of Technology repurposed into engines of destruction. Few knew their true form; even the broken husks recovered by the Imperium were capable of scouring worlds. It was whispered that just a few of these machines could challenge a Primarch.
Faced with the endless tide of traitors, Belial was prepared for the worst.
Suddenly, a voice that had been absent for ten millennia resonated behind them.
"Belial. Today's battle concerns the honor and the very future of my Dark Angels. Stand fast. Let Chaos know our fury and our resolve."