After you kill Ian in Briar Valley return to harry and he will tell you he isn’t feeling well and will send you to Sharon. She will send you to Kai to retrieve medicine to fix Harry.
Once you get to Kai speak with him and he will begin to tell you a story about Harry’s father. ONce he finishes he will give you a potion and tell you to make a bucket of lava and take it back to Harry to drink and heal him.
Quest will be completed once you return to Harry.
Kai Coordinates: X:-161 Y:68 Z:-2612