Monster Slaughter: Underground

From the publisher:

The old cabin in the woods may be remote, full of hiding places and infested with monsters… But who ever said it's revealed all of its secrets?

Monster Slaughter: Underground expands the original game by adding a new room to the board and new special guests for your monsters to overcome. These guests will have their own scenarios and special rules to shine in the limelight, but your Monsters will also have access to the new abilities to keep up the pace!

You need the core game Monster Slaughter to play with this expansion.