I tried this over and over again with all methods but I can't kill them as fast as they are doing damage to me. It's dumb..I'm on story mode and I've completed this before but I don't ever remember redoing it like this...I even saw a YouTube video and that guy smoked it without hardly taking damage(this was posted couple years ago). I try and I'm half health within the first few seconds...this shouldn't be this hard, especially on story lol.