In the city of Waterdeep rests a tavern called the Yawning Portal, named after the gaping pit in its common room. At the bottom of this crumbling shaft is a labyrinthine dungeon shunned by all but the most daring adventurers. Known as Undermountain, this dungeon is the domain of the mad wizard Halaster Blackcloak. Long has the Mad Mage dwelt in these forlorn depths, seeding his lair with monsters, traps, and mysteries—to what end is a constant source of speculation and concern. This adventure picks up where Waterdeep: Dragon Heist leaves off, taking characters of 5th level or higher all the way to 20th level should they explore the entirety of Halaster’s home. Twenty-three levels of Undermountain are detailed herein, along with the subterranean refuge of Skullport. Treasures and secrets abound, but tread with care!
The entity known as Oreiax is a gruesome, stunted monstrosity born of ancient death. Rescued from an eternity of petrification by Doresain the Ghoul King, Oreiax immediately pledged itself to the Ghoul King's service, and thus indirectly, into Orcus's service. Oreiax, born of stone and death, seeks to glorify Doresain by petrifying the world. Pgs. 112-119
Kravenghast Necropolis is hidden in a valley that was formerly part of a now dead city. It consists of a small cemetery that sits atop an abandoned necromancer's laboratory. The necropolis has been refitted as a temple to Vecna, the undead God of secrets. The mausoleum in the cemetery contains a secret spiral staircase that leads to the underground laboratory. The temple is populated by a twisted cult of Vecna, led by the lich-priest Mauthereign. Pgs. 96-103
On the outskirts of town lies an ancient temple to an unknown deity. Periodically, undead creatures issue from the catacombs beneath it. The party receives a commission from the city elders to venture into the catacombs and exterminate the undead. Pgs. 64-71
The Tower of Zoramadria is hidden away in the Feywild. The tower is an arcane academy under the tutelage of the lich Parthal. Parthal and his students lead serene lives of study and contemplation, except when they engage in a bout of bloody necromantic research that requires innocent souls as vital components. Parthal has a score to settle, and the Feywild itself might shudder and scream before the lich has had his revenge on those who killed his love. Pgs. 104-111
The desolate, uneven country known to locals as Battlefield Downs is strewn with the scattered remains of the ancient dead. During the last terrible years of the old empire, a series of grinding military engagements played out across the rolling fields of Battlefield Downs. In one battle that was part of a wider, disastrous campaign that contributed heavily to Nerath's downfall, the Empire of Nerath's legions clashed here against ravaging gnoll packs. It is now a haunted place, where only the bravest dare to tread. Pgs. 72-79
Floating Eternally among the endless silver void of the Astral Sea are vast, once-living islands, cast-off flesh of primordials and deities who lost their lives sons past in a great war. Today these colossal outposts bear mute testimony to the date of even the mightiest among us. Pgs. 120-127
The lost Bloodtower has returned, arising from its earthen grave to stand as a mute sentinel over the fog-shrouded moorland. In the weeks since it's return, local travelers have spoken of new undead roaming the countryside. Pgs. 80-87
A Conspiracy of Doors is a Dungeons & Dragons adventure for five player characters of 11th level. It can serve as an introduction to Sigil, the City of Doors, as well as a group of adventurers' first taste of action at the paragon tier.
The Auburn Desolation is a forsaken waste of treacherous sand and unbearable heat within the Shadowfell. Gloom-wrapped serpents and foul undead haunt the wastes, striking out at unsuspecting travelers from sandy graves. Pgs. 88-95
The rough ground on the outskirts of the village of Col Fen once served as a graveyard for an evil temple destroyed long ago. A recent disturbance released some of the ancient evil buried here, and now the dead in this graveyard are beginning to walk. Several villagers have already vanished and more will die if the undead are not put to rest. Pgs. 56-63