A Four-Year-Old Girl Must Save Warhammer and Humanity

I recommend skipping the Honkai Impact 3rd arc, because it's really bad.

Answer: Traitor

I'm no good at writing a synopsis: This is a story about someone who becomes a Xel'Naga in the world of StarCraft II.

Then, by a twist of fate, they also become the Emperor's mother and the Primarchs' grandmother.

For the sake of humanity, they must rescue the Imperium from the dire straits it faces in Warhammer 40,000.

P.S. The story starts in StarCraft II. The following worlds include Black Bullet, Gears of War, Akame ga Kill!, and Dead Space.