Level 17: Seadeeps - Waterdeep: Dungeon of the Mad Mage

Level 17: Seadeeps. Seadeeps is designed for four 14th-level characters, and adventurers who defeat the monsters on this level should gain enough XP to advance to 15th level. Before running this level, consider reviewing the "Gith" and "Mind Flayer" entries in the Monster Manual, as well as the "Ulitharid" entry in appendix A. They will help you roleplay the monsters on this level and bring their conflict in Seadeeps to life. What Dwells Here? Mind flayers from the Underdark have formed a new colony on this level of Undermountain, though githyanki from level 16 are determined to wipe it out. Mind Flayers Deep in the Underdark, a githyanki vanguard force attacked a large colony of mind flayers controlled by an elder brain. Fearing the colony's destruction, the elder brain instructed its most loyal vassal, an ulitharid called Extremiton, to establish a splinter colony somewhere safe from githyanki incursions. Extremiton made its way to Undermountain with a group of mind flayers, laid claim to level 17 of the dungeon, and began fortifying it against attacks from the githyanki and others. The dungeon's proximity to Waterdeep guaranteed the mind flayers a limitless supply of brains to feed on, while Undermountain's existing defenses offered an unprecedented level of security. Enemies at the Gates Through methods unknown to the illithids, the githyanki vanguard force tracked the survivors of their attack on the colony to Undermountain. Having recently secured the nearby Crystal Labyrinth (level 16), the githyanki now wage war against the mind flayers in Seadeeps. Uncertainty about its own future has forced Extremiton to hold off on transforming into an elder brain. Instead, it is focused on defending the colony and destroying its githyanki neighbors. With only a dozen mind flayers remaining under its rule, Extremiton has resorted to breeding a neothelid (see appendix A) and plans to set it loose in the Crystal Labyrinth to finally wipe out the githyanki force. Extremit...