For event information, see this quest entry.
The three clockworks in the room must be killed. They will be activated one at a time (random order) - one after the death of the previous:
Spawning throughout the entire encounter are a mechanical contraption which AE a low-resist stun if not disarmed in time.
Nurtha appears again after the clockworks are killed. She is at 3% health and will attempt to flee. Kill her to complete the event.