We try to kill him once, and I (Dagny, the healer) end up dying early in the fight because of a slight miscalculation about how much aggro you get for putting someone in extreme agony as their life is slowly drained from them. Right, so the party wipes, we go back, and this time I stick to a more pure healer role, not hitting the guy at all. This worked a lot better - I was able to keep us all up for a very long time before he even noticed me standing there... A quick Fade once and he's back off me... for about 15 seconds. Then he's back on me and I'm trying to heal myself, and shield myself, and I just Can't Keep Up. I die. But in the meantime, the rest of the group is victorious, and we defeat The Butcher.
I get quest credit for the kill, and all that's left is for me to be resurrected by the party paladin and burn the defiled corpses of two peasants, letting them get to their final rest. Loot dropped - mediocre loot, but good enough cloth shoulders to be interesting to two of us. And a scourgestone. I waited to be rezzed... and waited... and waited...
That's when we heard that the dungeon had stopped responding to other people who were in it. And a lot of other dungeons, too. The servers crashed, when I was *between* the stages of the quest. On my screen, Deobryn running into a wall, Snique was looting the corpse, and I was lying on the ground. Chat was still working, so we got to hear about what was going on, and some people were reporting on what was happening in the forums, but it sounds like it was a widespread problem that happened at the worst possible moment for our group.
Oh well. Guess I get to do it all over again sometime. Maybe next time I'll be a lot better at not dying while doing it.