Board Thread:Warhammer 40k General Discussion/@comment-8257990-20130509201630/@comment-32579200-20180622132643

It was stated on 40k Theories that the Hrud could have had a hand in creating Tzeentch, due to their entropic fields causing mass physical change around them. That could also be why the Maelstrom exists, it was created by the Hrud in a similar manner to how the Eldar inadvertently created the Eye of Terror. And this can be supported by the high numbers of Hrud in the Maelstrom.