The timer that kicks in when you get detained is too damn low, it's like 3-4 seconds. For 15 minutes we were just fighting these and barely doing any damage to the boss since I needed a machine gun for the detainment because I'd often run out of shotgun ammo...this would mean I couldn't use a sniper, nor could I use a rocket launcher on that boss. The add spawn is too much, we tried to stay in the area slightly to the right of the entrance where you have goblins and hobgoblins spawn (so we'd take them out in no time) and one of the silver goblins would always come walking towards us. Basically once we got that down we had no trouble actually getting the buff and getting the detainment out...but we had nothing to shoot the boss with. Also personal annoyance, even if you bunch up together you get more than one detainment shields at weird angles.
Then we used 3 horn and got him down in 30 seconds, so I said fuck it if the game wants to be cheap with me then I will shamelessly be cheap with it and use Ghorn.