Well, we've located the Legion's final base on the ridge - Invasion Point: Annihilator. It lies northwest of Forge Camp: Rage - and it houses a warp-portal through which the Legion has been drawing its reinforcements!
You've got to close that portal to prevent any more demons from coming through. The Point's overlord, Warbringer Arix'Amal, holds the portal's activation key. Take it from him and shut that blasted gateway down!
Upon completion of this quest you will gain:
+250 Honor Hold faction
Great job! That should drastically cut down on the number of demons trying to creep up our backsides. I can't thank you enough for your help out here, <name>.