Board Thread:Warhammer 40k General Discussion/@comment-98.81.158.208-20140213190331/@comment-5.69.1.93-20151115140927

The Horus Heresy books hint that the Emperor somehow begged/borrowed/stole his psychic powers from the chaos gods via a direct warp portal on the planet of Molech. He used much of it to create the Primarchs. The rest, to turn himself into the most powerful being in the galaxy. The chaos gods didn't lie to Horus (he'd have seen through any lie), but they didn't tell him the full truth either. Typical Tzeenchian JUST AS PLANNED.

In my opinion, Emps probably started out as an exceptional psyker, and possibly a perpetual as well, much like John Grammaticus but greater. He somehow managed to defeat the C'Tan known as the Void Dragon and, without spacecraft, imprison it on Mars (canon!) -- presumably by transporting himself through the Warp. So he must have always been pretty damn powerful, although that's nothing to what he became later.

Then, again in my opinion, that during the Age of Strife he biologically improved himself with the same sorcery-genecraft he used to make thunder warriors and Primarchs; the reason why there are no stories about a 12 foot tall giant guiding humanity before this is because he wasn't 12 foot tall before he altered himself.

So by the time he got to the great crusade he was incredibly more powerful than he'd ever been before; indeed, truly godlike. He just didn't start that way, or he might have been able to do something about the Iron Men or the collapse of human civilisation.