The Seventh Book by Wuren Xingchen

Lin Xingyun is reincarnated as a demon god in the world of Genshin Impact: the Thunderstorm Demon God, Qileixius. He saves the first Electro Archon, but is eventually sealed by Khaenri'ah within Dragonspine. Years later, the Traveler's arrival sets him free once more. “Hahahaha! I'm back!”