The Undermountain Module implements part of the Scoundrels of Skullport board game expansion. The rest is implemented in the Skullport expansion.
This adds a new location to the Lords of Waterdeep. This has unique characteristics and offers new play options, including new Lords, Buildings, Intrigue, and Quest cards.
Undermountain is a vast and multileveled dungeon beneath Mount Waterdeep that once served the crazed wizard Halaster as a site for magical experiments. Now it is a labyrinthine maze with few refuges for weary adventurers.
The rumored wealth of Undermountain entices adventurers to brave the mysteries and monsters beneath the City of Splendors. The risks and the rewards are greater for undertaking Quests that require more Gold and Adventurers.