Chaos moved against the Imperium. Between realspace and Warp, Vashtorr's Arks of Omen tore through physical law.
These gigantic warships, forged by three hundred Daemon-Forge Worlds, each bound a greater daemon in its engine core.
The Arks of Omen themselves were super-ships, cobbled from wrecks lost in the Warp and reforged.
With their daemon engines installed, Vashtorr distributed them to his Chaos champions and lords, announcing to all Chaos forces:
Help him gather certain "keys," and a Arks of Omen would be their reward.
When a bronze ram prow pierced the veil of reality, the surprise assault on the Imperium began.
These ships were larger even than a Gloriana-class battleship—true cosmic siege engines.
The Imperium could only compare them to the Phalanx, and to Lord Rhodes' Pedan super-carriers—of which only a few existed, all with the Indomitus Crusade.
Chaos raised wars across the Imperium, worst in the Imperium Nihilus.
There, only Aeldari Webway routes and the Nachmund Gauntlet connected through, so Chaos ran rampant. Many Imperial worlds were forced to defect.
Guilliman, on Holy Terra, processed mountains of paperwork daily. Thankfully, Malcador shared the burden; otherwise even a primarch's body would falter.
Sanguinius, Lion El'Jonson, Rogal Dorn, and Vulkan had received orders to deploy to the Imperium Nihilus to aid worlds under attack.
In the Sanctus Imperialis, Rhodes' two sons had come of age and each led their own legion against Chaos.
Accompanying them was the human War God Khaine—this primarch now commanded his own legion as well.
Cloned Lorgar, Magnus, and Guilliman themselves held the Triarch posts.
"Now we must hold the Imperium Nihilus no matter what," Guilliman said, using a special link through cosmic beasts to speak with the primarchs already en route.
The war had exploded without warning. Chaos had emptied its nests to assail the Imperium; many worlds fell at the first blow. The primarchs had to race from fire to fire.
Worse, at this critical hour, Father and Rhodes were extracting a Chaos godshard—no interruptions allowed. The primarchs would bear the burden.
"Guilliman! What exactly are Father and Rhodes doing? Can't you tell us?" the Lion asked.
Aside from Guilliman, who was executing the plan, the other primarchs knew nothing specific. They thought the Emperor had destroyed Fulgrim and recovered Corax; beyond that, only that something huge was underway on Terra.
"And how is Corax?" Sanguinius asked.
"My brothers, I can tell you what Father is doing—at his instruction: he is extracting a Chaos godshard.
He has no time to tend to Corax; several cosmic beasts are purging his Chaos taint.
Rhodes' men have crafted him a new body; in time, he will recover," Guilliman said.
Persuaded by Rhodes, the Emperor had decided to hide less from his sons this time. He ordered Guilliman to explain upon inquiry and lay bare the gravity of the situation.
He had paid dearly before for secrecy and half-truths—his sons fractured from him.
He would not repeat that mistake.
"So that's it. If Father and Rhodes succeed, we can permanently erase a Chaos God?" Horus said.
He had never imagined such a grand design.
The other primarchs were shocked too—to think the detested Chaos Gods could be undone in this way.
"For now we're only extracting the shard. Once removed, Rhodes will purify it. Whether we succeed depends on what follows. Chaos has likely learned of Father's plan—hence their frenzy," Guilliman said.
"No wonder those Chaos wretches have been so brazen. Tell Father not to worry.
We will quell every rebellion and drive them back to where they belong," the Lion said.
The primarchs nodded. This was a moment of life and death for the Imperium—no slackening.
"My brothers, it's worse than you think.
I entered the Golden Throne recently. Father told me that when the shard is fully taken from Fulgrim, an unprecedented disaster will erupt.
The entire Sol System will, because of the shard's manifestation, become a place where the Warp entwines with reality. In other words, there the Chaos Gods can wield their true power," Guilliman said.
What the Ruinous Powers perceived, the Emperor and Rhodes had also foreseen.
At the instant of extraction, Terra—and likely the whole Sol System—would see the barrier between reality and illusion sundered.
It would become coexistent with the Warp. They would not even need the Webway link via the Golden Throne; endless daemons could pour into Terra unhindered.
So the Emperor had ordered evacuations from Terra, Mars, Luna, and other Sol worlds—civilians and key assets alike—anticipating Terra might become a battlefield.
"What? Guilliman, you're joking. If the Chaos Gods can descend in person—you know their power. Unless Father rises from the Throne
and awakens the Dark King within—otherwise, any one Chaos God could defeat him—and easily," Horus said.
He even wanted to rush back immediately. Wielding the Giant of Light, he could, to a degree, contest the Warp and be his father's strongest aid.
"Don't underestimate our father. He has received ten millennia of mankind's prayers.
Even without the Dark King, he can go toe-to-toe with one Chaos God and not be badly outmatched," Magnus said.
He had been by the Emperor's side and knew how strong he had become—stronger than decades prior, bolstered by gifts from Rhodes and a flood of dark power.
When Warp and reality overlapped, the Emperor could also unleash vast might.
"The problem is, it could become three-on-one—or even four-on-one," Rogal Dorn said.
He had received grim reports. While crushing Chaos in the Imperium Nihilus, they had destroyed a Arks of Omen and pried news from a captured champion:
The lesser god Vashtorr sought a set of strange keys. If he gathered them, he could ascend as a fifth Chaos God.
They might eliminate Slaanesh, but a new Chaos God would emerge.
If he joined the battle on Terra, Father would face four foes. He might then be forced to awaken the Dark King—and mankind would be doomed.
Silence fell.
"We must stop it. Wherever a Arks of Omen appears, we go first and destroy it. Vashtorr must not succeed," the Lion said.
Under emergency orders, he had recalled all Deathwatch expeditionaries and hunted down the Fallen in the Warp. The Dark Angels were back to legion strength—hundreds of thousands.
Whatever schemes awaited, he would meet them.
"I've discussed this with Rhodes. He has arrangements and says if his plan works, Terra will not become a battlefield and the four will not emerge from the Warp," Guilliman said.
What he'd described earlier was the worst case. Rhodes had countermeasures, though he hadn't shared details.
"If it's Rhodes, I believe him," Horus said.
Without Rhodes, the primarchs would not even be reunited.