Carnifex Korum spawns in the basement of the government office building (PHs are the carnifex mobs in the four square rooms in the center area of the basement).
this guy is a pain the butt if u just fight him in the open. I suggest u clear the prison cell next to where ever ur camp is, and pull him inside the Prison Cell and kill him to advoid being thrown around into adds. The Prisoners Assist him but are not kos so you need clear them first.
Every 20 seconds casts <Torture>, 41k DD with push back and up components.
It must be a limited area effect spell as my group only had one other member get hit and some mercs which were standing semi-close to me. After I moved further away I only saw one merc get hit again, though we didn't kill it, so perhaps I'm wrong.