The quest works fine, but the issue is with the spawned monsters AI
The purpose of the quest is to defend the altar against monster until time run out. However, most of the time the monster will ignore you and go straight to the altar, no matter what you do they won’t turn aggro. That’s fine, I’ll just have to CC them then. Well, they are immune to CC as well.
Took me several tries and a spark of luck when the monster aggro work on me to complete this quest. I don’t think that’s how it should go.