Start by having Koss in your party. Go outside Rilohn Refuge and talk to Wekehsa. After Koss and Wekehsa talk, follow Wekehsa, but make sure that he doesn't get too far ahead. You will encounter various types of drakes including; Irontooth Drakes, River Drakes, Lightning Drakes, Grand Drakes, Sand Drakes, and Obsidian Furnace Drakes. When you get to the quest marker, you will see Lord Yama and some Vabbian Guards. When they turn hostle, kill them (not very hard with a full party). Once they are dead, talk to Wekehsa for your reward.