Do you mean the spooky 'Scary Movie' like figure? He's quite tough indeed. You have to be really careful predicting his movements. Easier to avoid it, but more satisfying to kill it ;-)
He doesn't show up all the time, but when he does I tend to just run and try and keep walls between us. He's not a boss, but he's a rare spawn powerful creature. (Perhaps not as rare as he should be, haha)
