What quest is this?

[Pratt2]

There's a quest that I think is in Act 1 (maybe 2) where there's a checkpoint in an open courtyard (usually has a shrine and maybe an elite pack) and you then enter a large building where a huge wave of mobs spawns when you reach the bottom of a curved staircase. Then you run up the staircase and up into 2 rooms with big double doors at the end. When you go through the doors you see Maghda talking to a bunch of cultists who then attach you.

Anyone know what quest that is? I know it's pretty vague. Thanks!

NVM - Found it.