Speak with a Halasian ghost who spawns on the island with all the gravestones upon completion of all five of the gravestone quests. ( 180, -18, 148 ) Copy/waypoint 180, -18, 148
Simply progress through the dialogue with the Halasian ghost, who turns out to be the ghost of Karg Icebear. The quest will complete upon finishing all the dialogue.
Make sure you go through his text quickly, since he seems to have a fairly short timer. If he despawns before you can complete his dialogue, then delete the quest, zone out, and come back to spawn him again.