Seeing Nirvana flash a sinister smile toward him, Chen Hao suddenly became alert, pondering what differences there might be between this ghostly form and the previous demon soul and beast soul forms.
Although it was a ghostly form, the Nirvana in front of him was still different from a typical Yin Soul—his physical body was alive, but not in the form of a Yang Spirit. Instead, it was a mixed form developed on the basis of a Yang Spirit through the cultivation of demon souls and beast souls. It was this particular aspect that allowed Nirvana to be reborn after his demon soul and beast soul forms were killed by Chen Hao.
As for how to completely kill Nirvana, Chen Hao didn't know at the moment. However, given the current situation, the demon soul and the beast soul forms that he had killed should no longer be able to resurrect. Everything would only be settled after he defeated Nirvana's current ghostly form and any possible upcoming demon soul forms.