I avoided the whole second phase of combat and finished the entire encounter in 2 rounds. My thief character had initiative. I drank some green tea, then did backlash on Lucian. From there, adrenaline > daggers drawn > skin graft scroll, repeat 3x... Lucian should be at around 2,000-2,300 health. One more time (adrenaline etc) triggers Lucian's dialog just before the second battle starts... however daggers drawn attack is still going and kills him before the dialog finishes and he drops dead. From there all my characters used green tea and the remaining skin graft scrolls (I had 6) and mopped up everyone else taking barely any damage.