In the void of the Lythera IX sector, a warship hung silently.
In the command center deep within the warship, an equally hulking figure sat on a throne composed of countless streams of data.
His body was deeply integrated with the throne's cables, and countless green streams of data-light flowed over his heavy Terminator Armour, which resembled a mobile fortress.
The former Primarch of the IV Legion, the Lord of Iron, Perturabo.
Dozens of holographic projections hovered before him. Each broadcast the breathtaking battle on Lythera IX in real time from a different angle. There were wide views from high orbit, close-up views from miniature drones disguised as rocks, and even energy views simulated through analysis of fluctuations in psychic power.
Expressionless, Perturabo watched Horus see through the trap, suffer a cut, then unleash even greater strength because of his injury and ultimately overpower Mortarion.
His fingers tapped lightly in the air as countless streams of data flashed before his eyes.
"Target: Horus Lupercal... bioenergy response exhibits exponential growth after injury... growth model conforms to no known laws of biology or Warp daemonology..."
"Conclusion: anomalous variable. This individual is not the Horus I know."
There was no surprise in Perturabo's eyes, only the cold, inquisitive contemplation of a mathematician who had discovered an entirely new irrational number that no existing formula could explain.
"Mortarion... foolish. Still employing stale tactics from ten thousand years ago. Failure is inevitable. Probability: 97.3%."
He watched Mortarion get blasted away by a hammer blow in the projection and crash ignominiously into a wall.
"Calculations complete. Mortarion's defeat is now a foregone conclusion. Next, Horus will banish him, and then..."
His projections were interrupted at that moment.
A completely new variable, rife with chaos and unpredictability, had barged onto the board in the most brutal way