@Cardinal It was explained in the beginning. He has a heavenly body or something like that. Thanks to that he can use the book of heaven and earth which are incredibly powerful techniques.
Spoiler!
The Descent of the Patriach, Fated Villain, My Female Apprentices Are All Bigshots From the Future, Tales of a Shining Sword, Cosmic Heavenly Demon 3077 are goated 😎