Waterdeep: Dungeon of the Mad Mage

Twenty-three levels of Halaster Blackcloak's Undermountain.

Waterdeep: Dungeon of the Mad Mage is a 5th edition Dungeons & Dragons adventure released on November 20, 2018. It is the second part of the Waterdeep storyline, after Waterdeep: Dragon Heist, and the first official 5th edition adventure written for tier four play, levels 17 to 20.

Quick Facts

Edition: D&D 5th edition
Released: November 20, 2018
Tier: First official tier-four (levels 17-20) adventure
Villain: Halaster Blackcloak
Follows: Waterdeep: Dragon Heist

Facts from the source article.

Background

Undermountain is the lair of Halaster Blackcloak, a wizard who went mad as he dug ever deeper beneath Waterdeep. Its levels hold the creatures he has overpowered and portals to other parts of the Realms and the multiverse. The adventure starts in the Yawning Portal tavern and runs through twenty-three levels of the dungeon and the hidden port of Skullport, a link to both Waterdeep's underworld and the Underdark. It draws on older Undermountain products such as The Ruins of Undermountain and Expedition to Undermountain, was announced in June 2018 at the Stream of Many Eyes, and reached number 18 on Publishers Weekly's hardcover nonfiction list in December 2018.