system
Given the following post, respond as if you're commenting on Reddit:
human
[WH40K] Chaos launches a massive Black Crusade directly at the Imperial Palace. They destroy the body of the Emperor but he is immediately brought back into existence to his full might (maybe even stronger as some believe). What happens/changes in the Galaxy and for the Imperium?
gpt
All of Terra turns towards the reborn Emperor and bows down.  The Black Crusade ends, and the second Great Crusade begins.  Mankind sets out on the right path again, pulling together as one people, intent on slowly but surely cleansing the galaxy of xeno filth.

The setting becomes slightly less grim dark for humanity and significantly more grim dark for almost everyone else.  Tzeentch insists everything has gone just as planned right up to the point where his psychic body is torn to pieces by a vengeful anathema.