Reincarnated in the Apocalypse: I Stuff Zombies into the Underworld

The underworld is empty and evil spirits are in the world. You mutate and I cultivate immortality, and the zombie core is heavy. Unexpectedly, I, Zheng Qian, have been working in the underworld for a hundred years. I was asked to do all the backbreaking work, and all the benefits were taken away by the underworld. Then don't blame me for stuffing some dirty things into the underworld!