Location: Scholozar Basin, behind Freya
What to do: If your a level 70 looking for an easy way to level faster, just pay or find a friend with a Demo lock spec and have him run around the entire area doing hellfire and the voidwalker's sacrifice to last longer. You'll just be sitting there gathering XP like crazy as the mobs instantly respawn. You can also gather TONS of frostweave cloth here.
Location is number one on the map behind Freya: