Scoundrels of Skullport adds two new expansions to the Lords of Waterdeep board game — Undermountain and Skullport — inspired by the vast dungeon and criminal haven under Waterdeep. Players can choose to include one or both expansions in a Lords of Waterdeep game. The expansions also allow the addition of a sixth player.

The Skullport expansion adds a new resource to the game: Corruption. The Undermountain expansion features bigger quests and more ways to get adventures. Scoundrels of Skullport also includes new Lords, new Buildings, and set-up materials for a sixth player.