"Ruins of the Umbral Tower" is a shadow fey hunter lair suitable for four or five 8th-level characters. This adventure can be completed in a single session. The ruined Umbral Tower rests deep in the forest, in a marshy region avoided by all but songbirds. Long abandoned by its original occupant, the tower features a malfunctioning gate that connects this place and the Plane of Shadow. The site serves as a base for a group of shadow fey hunters and their entourage of hounds and guardians. The hunters used the gate to travel from their home plane, and they now attempt to bag as many trophies and as much loot as possible before returning home when the gate reactivates.

Something lurks in the shadows inside the caverns under the hill called Brin Brenin. Ancient enemies of mankind have returned for revenge, starting with the tomb of a long-forgotten hero. Somewhere inside are answers to forgotten questions, deadly monsters, and hidden treasures.