"Nether chart?"
Having learned the name and main function of this spiritual object from its Primordial Spirit, Gu Yang's eyes lit up.
Its primary functions include two aspects - one is to devour souls.
All souls swallowed would transform into ferocious ghosts, wronged ghosts, and so forth inside it.
The other function is to release ferocious ghosts and wronged ghosts to fight enemies.
The entire process fully automated, user-friendly. Even those who haven't practiced dark arts can refine powerful ghost kings.
However, the cultivation level of the soul before death is retained after transformation by the Nether Chart. It's impossible for it to evolve further.
This means that the Nether Chart's power depends on how many ghost souls you have collected - winning by either quantity or quality.