From Zone in of Kernagir, head North up the flight of stairs all the way up to "Dvalger Quickwrench". Face South west till you see the bridge. He paths beyond and on top of bridge, be warned he scowls at you if your not Invis. Bring a decent group/tank. You have to kill him 2 times. My advice tank him on the bridge in center...
Beastboy-Stromm.