
Basically before eating San, Hwan has to possess him first (probably to absorb all his energy I assume). And in order to properly kill Hwan, it is best to do so when the ghostly spirit is possessing it's victim since the physical form is much more vulnerable hence Geumsun is trying to kill San as Hwan is residing inside the former. Hope my explanation is clear hehe

Oh yeah I remember! He was like Eunjae too. I mean Eunjae was saved by San when he was suppose to die and San was mistakenly brought to the underworld by 704 so their body and soul both have a broken bond that's why Hwan can freely enter them. I forgot that San was not a goblin to begin with. I was just so shocked that I forgot about it for a second.
What just happened in chapter 53? Is Hwan residing inside of San so he can hide away from Geumsan? I'm confused. Someone explain to me what happened?