Pastoral Little Wizard

A Book Seeking Ways to Refine Corpses, Raise Ghosts, and Control Insects and Poisons

I want to read a book similar to "Cultivation of Immortality: Starting from Refining the Corpse". It's a kind of magic that specializes in one skill, similar to that of General Hengha, but the protagonist can practice more. He can raise ghosts, control insects, and refine corpses to learn the art of evil.