Honkai Impact 3Rd: I'm the Captain, but First and Foremost, I'm a Praetorian Guard

(This is a remake of my previous book. Even I couldn't stand reading the old version.) (This book has no female lead.) He transmigrates to Warhammer 40K, during the Unification Wars of Terra. Wang Bohai is chosen by the Emperor as an infant and, after enduring countless trials, becomes a powerful Custodian. As someone who knows the story, he uses his status as a Custodian to take part in all sorts of events, doing everything he can to prevent the Horus Heresy. But even though he gives it his all, he still can't stop the inevitable. During the War Within the Webway, he exhausts himself fighting off the demons to cover his companions' escape, then collapses beneath their assault. When he opens his eyes again, he has transmigrated to the world of Honkai Impact 3rd. His Custodian body and equipment have come with him. Having some knowledge of Honkai Impact 3rd's story, he decides to help the people of this world.