The Emperor parried an attack from Horus by time traveling to Cthonia

His parry is particularly impressive. He parries your swing with Cthonia. You are on the flat top of a dirty rockcrete parapet above a stagnant spillway. The radioactive glare is as harsh as the stink of the place. He is making His riposte, war-sword glinting in the ionising light. You knock it back, then you pitch ruthless blows at one another as you move along the lip of the decaying bulwark. Did He think that memories of your wretched childhood here would prise open your guard? Manipulation of the psychotecture to wrong-foot you is an impressive trick–
No. Great gods, this is Cthonia. He hasn't just refashioned the psychoscape of your Court as a makeshift weapon. He has shifted you both across the three dimensions of physical locality, and the fourth of temporal placement. This is Cthonia, the hinterland of the Athonat Exhaustion where the territories of the Catulan and the Justaerin clans meet in dispute. This may be the very day on which you were found.
He can see your surprise. He pushes in to exploit it. You hammer away a series of aggressive sword-strokes. In pulling off this trick, He has revealed His understanding of your domain. Not just your Court, but the wider realm of Chaos that inevitably surrounds it. He has grasped that everything, and everywhere, and everywhen, meets here in your isochronal nexus, conjoined by the warp, and thus that everything, and everywhere, and everywhen, is accessible.
It's not your father's power, it's what He does with it.

- Siege of Terra: The End And The Death - Volume three