The Deist cavern is split into three independent routes, conveniently corresponding to the three staircases down from the first floor. The first time you come here, looking for the pendant, you will only be here a very short time. The pendant is found almost immediately after taking the northeast stairs. Do not bother with the southeast stairs until you have the wyvern egg, since your goal will be to bring it to the spring found on that route. The third staircase, in the southwest, contains only treasure, so feel free to take that path at your leisure.