Go to the South end of Cliffs then go down the cliffside to the beach, you will find a Cliff Dweller's camp there with 2 tents and a camp fire, get between the water and the tents, then face due East from location of about 6.4K x 49.6k. He will spawn in the tent flap opening of the left tent, but only after you have killed lots of the other Cliff Dwellers first. There were only 2 of us, myself (brand new lvl 42 Ranger) and a good friend/guildmate who is a lvl 50 Warden. I pulled from the location given above with my bow and got 3 arrows, we almost always got 2 Cliff Dwellers on us, but when Brarn was pulled he brought 5 friends with him. We both died (was my fault) but I got the pants, then Brarn re-spawned again very quickly.