The Emperor paid no heed to Angron's hostility. He was considering exactly which part of Angron Draudillon's resurrection magic would revive.
Would it revive the flesh? The soul? Or something deeper still?
Though he had thoroughly searched Draudillon's soul, the Emperor still could not determine the core principle behind resurrection magic. The natives of that other world understood magic only at the superficial level necessary to barely use it; they had never delved deeper into the fundamental principles underlying its construction.
Magnus was much the same. His face was full of arrogant contempt for the natives' backwardness, yet he did not realize that his own exploration of the Warp and psychic arts was even more childish—and far more dangerous.
Nor could he personally travel to the other world to conduct experiments. The disturbance caused by his disappearance would be far greater than that of a Primarch; even if Malcador burned himself to ashes, he could not conceal it.
Yet the Emperor's intuition told him that resurrection magic could not function properly in their world of shattered laws. Angron had to complete his rebirth in that orderly other world.
But before that, the Emperor believed he still needed to make an effort for the purity of the other world. He had to eliminate everything that might contaminate its rules.
That meant the Warp essence sealed within the Primarchs' bodies, restrained by their humanity.
None of his sons knew this. Only Leman Russ, who had passed through the gate into the other world, had learned through the Emperor's silence that his birth had not been pure. But Leman Russ's Loyalty and trust in the Emperor overcame his curiosity and doubts about his own essence, and he restrained that restless Warp essence with his mind.
But the Emperor could not guarantee that Angron's