H.P Lovecraft vs Warhammer 40k

Let's have our main character a apostle to a old one.. In Warhammer 40k.. no connection to the warp.. But can use Eldritch magic with the risk of having too much energy in them causing a mutation.. to many and they become fully one of their patron.. allowing them to do whatever.. This is a big risk to the chaos gods so they don't threaten them in a bit of hesitation of having idk.. Narolethotep on their behind from suddenly having them fully mutate due to God level threat.