Oh, this is the one in the ruins where the goblins hang out. I solo'ed this one with my LM (36 or 37 at the time).

I approached him from the outside of the keep's back wall. There is a break in the wall near him where you can jump up on the wall. I left my bear outside the ruins, jumped up on the wall and threw a stun at him, then jumped back outside. All of the mobs near him aggroed and proceeded out the front door to circle around to where I was. I put my bear on agressive/assist, jumped back up on the wall and into the keep where he was stunned. I managed to take him down before the goblins could finish off my bear, who was now circling the other way to get to my target and met them halfway. Worked out pretty good, and I was able to map out before the gobbies got back to me.