Visit the back entrance to Blackburrow, which can be found inside a giant fallen log in a small valley hidden southeast of Archer's Wood. You can reach the valley by crossing two islands joined by log bridges starting with Wooded Isle around ( -765, -39, 988 ) Copy/waypoint -765, -39, 988. The quest should update when you walk close to ( -1214, -3, 912 ) Copy/waypoint -1214, -3, 912.
Return to Captain Beltho at The Keep of the Gnollslayers.