Edge of Civilisation - The West Reaches
Shrine to the Precursors
Appearing as a dungeon in the forests of Privora, the Shrine to the Precursors is a 2-level dungeon, the upper one which has been overrun by fungus, mould and other growths. The second (reached after solving the puzzle etched into a room) seems to be dedicated to the elements and the elemental planes. Within it was a wyvern that, after a battle in which it retreated, flew off out of the dungeon and into the forest. It wasn't seen again.