EADEEPS IS DESICNED FOR FOUR 1 4TH-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 githyankifrom level (^16) are determined to wipe it out.
MIN D 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. T he
dungeon's proximity to Waterdeep guaranteed the mind
flayers a limitless supply of brains to feed on, while
Undermountain's existing defenses offered an unprece-
dented level of security.
ENEMIES AT T H E 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. Extremiton is also gather-
ing thralls of every race to help defend the colony if the
neothelid is destroyed or fails in its task.
CITY OF T H E MIND
Extremiton can sense intelligent creatures within 2
miles of it and is able to communicate with them tele-
pathically. Using this ability judiciously, the ulitharid has
learned a great deal about the city above and its inhabi-
tants. Waterdeep has, in a way, captured the ulitharid's
imagination.
Extremiton intends to enslave the population ofWa-
terdeep, but not before it fully understands this strange
city and its people. The telepathic communications the
ulitharid has initiated with random Waterdavians has
provided it with plenty of information, but no firsthand
knowledge of how city dwellers behave and react on a
daily basis.
LEVEL 17 I SEAD£J::PS 221