Kill one of three groups of mummies in the western part of the Priestess' Court ( -109, 13, 108 ) /waypoint -109, 13, 108. Each group will drop an urn.
Place an urn inside the trianglular area in front of the picture. (Note: Only place a single urn in the triangle area. The urn will despawn and either the Rin Priestess of the Fyr'Un and 2 an offering retriever will spawn, or just the retrievers. They will often despawn if not attacked immediately. Respawn on the groups that drop the urns is about 5 minutes.