The druids built the Talon Den on Stonetalon Peak, where they keep many powerful items.
They devised a complex scheme to keep them from falling into the wrong hands.
Luckily, I managed to... extract some details from one of them.
Hidden in a small lantern at the entrance of the Den, you will find the Gatekeeper's Key--with it you will be able to open caches around the Den. The items from these caches will allow you to open their hoard, located in one of the central areas.
As the three keys are slid into their matching openings, in the middle of the glowing light a number of items appear.