The Duke mission is ridicules. The average player can't beat him on his own and the group attack is hit and miss. I have done this mission 4 separate times as in 4 agent reductions and have only once seen duke beat down. I could see attacking him and reducing his life by a bit but only a few players can take him alone. Why not give the single player a chance? The mission should be open ended so that on the off chance they catch duke being attacked they can join in and finish the mission.