Destroy 3 Fel Cannon MKIs in Forge Camp: Rage and return to Nazgrel in Thrallmar.
There is a second production facility, Forge Camp: Rage, that lies to the immediate northeast of Thrallmar. The demons have positioned a number of their fel cannons along the ridge - and they're aimed straight at us! You must enter the camp and destroy these fel cannons.
[player], you must be sure to detonate them all - or nothing will stop the Legion from raining fiery hell down upon our heads!