Are you supposed to fight 3 Manifest Corruptions on the quest Deep Disturbance in Shadowfen?

Ignotus

I'm doing this on Cadwell's Gold. It's a quest in the SW corner of Shadowfen. It has to do with some ritual that involves Namira. I get up there and a 90k+ mob named Manifest Corruption spawns. It's a lurcher type mob, at least I think that's what they are called. He's fairly tough, but killable. Then another spawns while I'm finishing the first one. The 2nd one kills me. While I'm waiting to respawn, another one comes running down the steps. They stack right beside the quest objective, so you have to fight 2-3 of these things at one time.

I abandoned the quest the first time thinking that it was bugged when I had 3 of them standing side-by-side at the bottom of the steps. Same thing happened the 2nd time, except this time I managed to kill 1 of them before all 3 spawned. I somehow managed to activate the quest objectives and only had to kill 2 of them. I think another spawned though after I killed the 2nd one, but I'm not positive about that. I'm thinking that maybe it's bugged and you should only have to deal with 1 of these things. Seems a bit excessive for a solo quest.

EDIT: Maybe it's legit judging by how they stand spread out at the bottom of the steps instead of stacked. If so, that's a pretty difficult quest.

Enodoc

From what I remember, yes, it's intended. The lurchers are designed to spawn indefinitely until you disrupt the ritual being performed by the two NPCs using whatever item you found during that quest (Hand of Namira?). Once the NPCs have been stopped using the relic, the lurchers should stop spawning.

Phranq

I remember this one on Silver.. the point was to ignore the lurchers and stop the ritual, at which point they vanish.