Deneb Walker is a level 45 scroll and potion vendor located in the Alliance section of Stromgarde Keep in the contested territory of Arathi Highlands. When you enter the keep, you will go under a bridge. After you go under the bridge, turn 90 degrees right, 3 times in a row. Then you will be walking east over the bridge you just went under. As soon as you cross over the bridge turn right, and you should run right into him. See List of Arathi Highlands NPCs.