In today's Underdark
preview, we delve further down into the Deeps, where we encounter Nihilath the Fallen Illithid Empire.
In the vast spaces beneath the thin layer of tunnels and caverns nearest the surface, passages can stretch for miles beyond measure. Adventurers who descend into the Deeps find that the hazards, threats, and immediate dangers are magnified tenfold.
All the terrible hints encountered in the Shallows of drow cities, vast illithid conspiracies, and sunless seas where aboleths abide find their awful fulfillment in the Deeps. In the deepest portions of the Underdark, mind flayers savor the harvested brains of their slaves and captives, great vaults flicker in the light of candles prepared from the fat of countless sacrifices made to Lolth by her drow followers, and subterranean seas thrash with aboleths intent on completing incomprehensible, decades-long rituals.
This region is an enigma; no one can ever claim to know its entirety. The total area of the Deeps far exceeds that of the surface of the world above. The twisting, convoluted tunnels that squirm through it hide more horrors than sane beings can imagine.
Chapter 3 of Underdark presents the following topics:
Denizens of the Deeps: Brief discussions of some of the cultures and monsters that frequent this region of the Underdark.
Typical Deeps Encounter: The characters run afoul of a drow hunting party.
Phenomena of the Deeps: Terrain, physical traits, and other features of the Deeps.
Erelhei-Cinlu: The city of drow most well known to surface dwellers.
Xarcorr and the Rock’s Roil: An aboleth colony whose very existence strains reality.
Sunless Seas: Watery environments are even more deadly in a land without light.
Past Masters: Mind flayers in the ruined empire of Nihilath quest for a return to their former glory.
The Buzzing Vaults: Peace and quiet are nowhere to be found in the secret realm of the swordwings.
Mherkrul: A refuge that both angels and devils use as a hiding place.
The Hatchlands: Birthplace of the beholders.
Deep Waters: A dungeon delve for paragon tier characters, in which they must rescue a kidnapped drow noble from a band of kuo-toas.
Scattered throughout the Deeps in small cities, splinter cells, and plotting concords, the race of mind flayers searches for brains, power, and a path to regaining its former status as masters of the Underdark and worlds beyond.
Nihilath, Fallen Illithid Empire
For paragon tier and epic tier characters
Even as the races of the surface world lament the ruins of their shattered civilizations, the illithids of the Underdark are tortured by an insatiable hunger for the glory of fallen Nihilath.
This vast empire spanned the still-expanding recesses of the Underdark throughout the first era of mortal history. Its gruesome living architecture filled the tunnels and caverns of the subterranean world. While the drow still huddled in dark corners and dwarves dug gold from shallow pits, mind flayers patrolled the Underdark with proud impunity. Their legions of slaves excavated countless passages, built towering structures, and kept the illithids fed with an endless supply of brains.
Their heritage enabled mind flayers to thrive in the early, ever-shifting Underdark. Imprinted with the twisted unreality of the Far Realm, illithids adapted easily to the constant shifts in Nihilath’s physical foundations. The later great subterranean settlements of the drow, dwarves, and fomorians came into being only when parts of the Underdark stabilized. Before them, the illithids allowed their empire to divide and subdivide in harmony with its fundamental chaos. As a result, Nihilath spread throughout the entire Underdark and far beyond.
No one can be certain of the true reason for the empire’s fall, though many tell a tale of slaves revolting successfully against cruel masters. The illithids themselves are silent on the matter, though whether this silence is due to ignorance or shame might never be known.
Dungeoneering DC 20: Mind flayers once ruled huge swaths of the Underdark, using armies of slaves to mine resources and build their empire.
Dungeoneering DC 30: This mind flayer empire was known as Nihilath, and it existed before the Underdark’s geography stabilized. Its living architecture adapted to constant shifts of tunnels and caverns, and today its remnants can be found throughout the Underdark.
Scattered through the Deeps, small cabals and communities of illithids pursue the hunt for fresh brains and for power. Each city is ruled by its own set of elder brains—vast organs that dwell within brine vats, encompassing the aggregated minds of the city’s dead. Though immobile and vulnerable, the elder brains are powerful entities. Even so, they are only echoes of the power of the original Ur-Brain that guided Nihilath.
Illithid histories claim that the first elder brain was formed in the Underdark, coalescing when the Far Realm first erupted through the Underdark’s brittle foundation. A fragment of brain matter was pulled through the breach and found a fertile sludge in which to take root and grow. The parasites it spawned were the first illithid larvae, crawling out to penetrate the minds of the Underdark’s primitive humanoid inhabitants and become the original mind flayers.
As the illithids built the empire of Nihilath, this first elder brain became an entity of unimaginable might, its power outstripping present-day elder brains by an order of magnitude. Unknown beings destroyed this Ur-Brain during Nihilath’s collapse, but even today, all illithids feel its ancient call deep in their minds. The mind flayers believe that a fragment of the Ur-Brain still lives, and that if a sliver of that tissue can be found, the Ur-Brain might be regrown. More important, the vengeful larvae it spawns might well remember all of Nihilath’s lost secrets.
As a result, mind flayers have become archaeologists of a particular sort, competing with adventurers and other treasure seekers for items and information that have any trace of connection with Nihilath or its ancient secrets.
A few of Nihilath’s secrets were not lost. Illithids grow their walls and battlements from ritually altered organisms imported from the Far Realm. Their towers breathe and perspire. Pulsing veins run across the surfaces of doors, which bleed when cut. Homes nourish themselves on insects and vermin, which the dwellings catch with lashing, gluey tongues.
The dessicated, long-dead structures in ruins left over from Nihilath indicate that the empire’s buildings, particularly its great fortresses, were stranger and more powerful than the domes, bulbous towers, and filamentous tubes that mind flayers grow in their present cities. Some sages believe that certain creatures, such as ropers and oozes, trace their origins back to the living fortresses of Nihilath.
Aberrant structures can be of any shape or size. They might resemble walls of mouths, sheets of stone-colored flesh, or tentacled towers. Some common effects of such structures include the following:
- Squares adjacent to an aberrant structure are difficult terrain.
- Creatures on or adjacent to an aberrant structure take a –2 penalty to saving throws.
- Non-aberrant creatures that end their turns adjacent to an aberrant structure take 5 damage per tier.
An aberrant structure typically fills 1 to 40 squares. It can be identified with a DC 30 Dungeoneering check.
As a predatory race dependent on the brain matter of sentient beings, mind flayers perch at the apex of the food chain. The scarcity of their dietary need restricts their numbers—even when they breed slaves as food.
The illithids of Nihilath supported a large population by way of a lost secret: the ability to cultivate brainmoss. This substance consisted of tissue seeded from living brains. Grown on cavern walls and floors, it provided flavorless but sustaining food for densely populated illithid cities.
Several varieties of wild brainmoss can be found growing in the Underdark today. Mind flayers can feed on wild brainmoss, but the secret of cultivating it for more extensive use has been lost. Reliable brainmoss cultivation would permit the illithids to multiply their numbers enormously.
Wild brainmoss picks up and retains strong emotional impressions of sentient beings around it. These emotions can have a significant effect on the minds of living creatures.
Wild brainmoss typically covers 4 to 10 squares of cavern floor or walls, usually as a contiguous patch. Different varieties occasionally grow in the same large chamber. It can be identified with a DC 25 Dungeoneering check.
Effect: Each variety of wild brainmoss has an effect on living creatures on or adjacent to it. Here are some possibilities:
- Gain vulnerable 5 psychic per tier.
- Gain resist 5 psychic per tier.
- Gain telepathy with a range of 10 squares.
- Gain a +2 bonus to attack rolls for psychic powers.
Usage: The presence of brainmoss can serve as a harbinger of illithid presence nearby . . . or it can signal characters to search the vicinity for Nihilath ruins. Some varieties make mind flayer encounters more dangerous, while others can help the illithids’ enemies triumph. Choose the appropriate variety—or varieties, for a particularly interesting encounter—that provide the edge to the side that needs it most.
Since the earliest days of Nihilath, the illithids of the Underdark have sought the rich flavors of brains steeped in emotion and experience. They captured and bred humanoid races as servitors and sources of nourishment. In doing so, they wiped out several sentient species native to the Underdark. Among them were the apelike ingai, the willowy dyath, and the large-skulled celeen. These beings inhabited Nihilath’s breeding pens side by side with drow, humans, dwarves, elves, dragonborn, and the race of gith whose escape gave birth to the githyanki and githzerai.
When the empire fell, most servitors died of predation or starvation. A few escaped. In some cases, entirely new races of the Underdark were born from the servitor races. Future descents into the illithids’ realm will doubtless uncover descendants of these servitor races.
Encounter: Deep Waters
The adventurers set out to rescue a drow noble captured by a party of kuo-toa raiders. The rescue might be the result of negotiations with the noble’s house, or of information discovered in the course of the characters’ previous activities. In any event, rescuing the prisoner provides a sure way to find favor with the drow—or to gain a bargaining chip for later use against the dark elves.
The kuo-toa raiders inhabit a warren of half-submerged caverns deep in the Underdark. Assume that the adventurers know the location of the site, or improvise a short skill challenge to allow them to find it. The delve opens with the adventurers on the edge of kuo-toa territory.