My Master Is Using Too Many Cheats in His Old Age

This person belongs in the heavens alone. There is no way to contact him in the mortal world. He wrote a book called A Hundred Ways to Murder Immortals, which became a bestseller across the Three Realms. It was especially coveted in the Demon Realm. From then on, kings stopped attending court, demon kings stayed up all night, ghosts shut down their markets, and the mortal world was no longer worth living in.