@Tfmonkey and of course praying Nurgle to remove the pain or Tzeentch to get a tentacle in place of your arm.
@Tfmonkey funny thing about 40K lore: the Emperor once fought great xenos who where the equivalent of the Great Old Ones.
https://www.youtube.com/watch?v=EKCCOx3GyVg
@Lorgar yeah Nyarlathotep is a corruptor, so he would be Slaanesh.
Nyarlathotep could also fuck with the Thousand Sons because he uses a lot of Egyptian motifs in his "Black Pharaoh" incarnation.