Hmm... now that'd be interesting. Of course, this would mean that all of 1-4,5 would be rendered unplayable due to the immense amount of corpses blocking off paths.
As for this picture, I know this spot like the back of my hand. Just after the first archway in 4-1, Vanguard Demon. Apparently our mage here didn't take the path left under the archway and (minding the trap panel on the floor, taking out the archers on the roof to minimize the possibility of further interference), sliding down the broken wall toward the skeletal archer, almost completely bypasses this behemoth. Actually, she could have fireball'd it from behind with impunity at that path exit, allowing her to claim one 'Gray Demon's Soul' which would provide a nice upgrade on a legendary item.
...I died to this guy far too many times to call myself smart about this, but far too many more times did I die to those damn black skeletons. Thank god for the Lava Bow.
He's easy until you get an invader that hides behind him. Then you just have to cloud or arrow him and having a staring contest with the BP until it finally dies.