Warhammer 30k and the Great Tomb of Nazarick

In a church of the Silan Theocracy that is about to be destroyed by the Great Tomb of Nazarick, an unclosable portal is found, connecting to the world of Warhammer 30K.

Thus, Warhammer meets the Great Tomb.

Ainz Ooal Gown: Damn, I'm a native!

PS: The original work is an expansion of my answer in "What would happen if the alternate world in Overlord was discovered by the human empire during the Great Crusade in Warhammer 40K?" The original

answer has been completed, and many plots of the fanfiction have been modified, which are inconsistent with the original answer. I hope everyone will support it.