In the book vengeful spirit page 331 it says the emperor got his powers because he traveled to the planet molech and entered a warp gate to speak with the chaos gods.
Emperor siding with chaos.
The answer is simple.
Chaos exists only to feed itself and feeding itself requires humanity to suffer.
We also know what the deal was the warmaster made the same deal though he bargained to get it whereas the emperor took it by force.
Chaos is not pro human and i am.
So i was watching an ach warhammer video about chaos lore and one statement he made has stuck with me for a bit.
I would side with the emperor just as i would always side with the imperials in any conflict in 40k.
How the emperor got his powers.
However there are several plays that are made where malcador expects a specific outcome and is instead met with a surprisingly opposite outcome.
Plus the deal isn t just known by chaos the perpetual alivia sureka who was asked by the emperor to seal the cave on molech after the emperor took the powers also corroborates the story.
The chaos knights also known as renegade knights daemon knights and the questor traitoris in high gothic are imperial knight combat walkers their fallen noble pilots and knight houses corrupted to the service of chaos.
Humanoid war engines that tower over their foes each chaos knight carries an army s worth of firepower upon its weaponised limbs and hulking carapace.
It then says that the emperor made a deal with the chaos gods who gave him psychic powers that his has today.