War Hammer: The reality Bender

"It’s a wondrous fantasy world where humans, elves, orcs, and the undead coexist!" he said. He completely forgot to mention the orbital bombardments and the fact that there is only war. Rowan, a reality-warping entity constantly hunted by the SCP Foundation, is offered a deal by a mysterious, golden-wreathed man: travel to a new universe, play the hero, and save humanity from a few pesky demons. Eager for a fresh start in what sounds like a generic isekai, Rowan agrees. Tricked by the Emperor of Mankind into dropping into the 41st Millennium, Rowan refuses to become just another casualty of the grimdark galaxy.  How hard could the 40th millennium possibly be for a reality bender?