I'll Kill Ghosts in the Cemetery for a Hundred Years

You wake up in a cemetery... The dead here can resurrect and climb out of the cemetery, and zombies and ghosts are wandering around, full of unknowns and terror. Fortunately, you have obtained a soul mirror, which can refine ghosts and extract various elixirs. So you just want to guard the tomb, eat, sleep, fight ghosts, and be a good medicine jar. But without realizing it, you have become the source of fear for the gods, the spokesperson of death, and the end of everything. Until one day, you punched the demon god who came to rob the tomb, and then you realized that you were invincible!