Heres the trick to this and the RED text appearing as you enter is VERY misleading. BTW i am a lvl 44 Balance shadow. I just ate whatever he threw at me popping my CD"s and interruted his "Benevolence"(Green Icon)
You DO NOT have to have Nadia out to defeat Stark. It does state that you MUST have Nadia but i just killed him using Fess. I wish i had known this earlier i would of used Fess a level ago.