This adventure is written with the intent that it takes place in the subterranean world called the Underdark in the world of Forgotten Realms, although it may be placed in other settings. Within the Underdark, Cyrog's lair can be placed anywhere though it is stated to be thousands of miles east of Gravenhollow. If you are running Out of the Abyss, you may want to have your players see the vision Cyrog Lives! Hail Orcus! (OOTA, 158). Additionally, it is recommended that this adventure be used for a party of 4 to 6 players, level 9 to 12. While merely hinted at through visions in Out of the Abyss, Orcus is roaming the Underdark unchallenged with an army of mind flayers at his disposal. Cyrog, the elder brain of a mind flayer colony in the Underdark has died. The demon lord Orcus has reanimated and taken control of it. The hive of mind flayers is now bent to Orcus's will through Cyrog as he strives to make all life in the multiverse into a vast undead horde under his control. The adventurers are contacted by a patron who gives them a special item (such as brain worms) to suppress their brain waves and make it possible to infiltrate the Cyrog's Lair without immediate detection. The adventurers must defeat or otherwise subdue mind flayers and a few guards, override the elder brain's mechanical defense system, and slay Cyrog.

The Fate of Faerûn Lies in Shadowy Darkness! Daggerdale is reeling from a sudden series of murderous drow raids. As a grave threat to the entire surface world develops in the war-torn dark elf city of Maerimydra, intrepid heroes must discover its source and destroy it, if they can.

The most deadly dungeon ever devised! High-level characters brave the unexplored corridors of Deepearth to confront perhaps the most feared adversary in the AD&D game. The second chapter of the Bloodstone Pass saga follows the conclusion of the desperate war against the bandit army. A cold and bitter winter drives the villagers to the edge of starvation, and numerous horrors strike the town of Bloodstone Pass. Join the adventure as the heroes explore the depths of the ancient bloostone mines, now inhabited by fearsome demons. There they hope to uncover the fantastic treasures rumored to exist in the unknown darkness. But deep within the mines, all is not what it seems.... This module uses the new rules from the Dungeoneer's Survival Guide and Wilderness Survival Guide. The adventure also includes optional BATTLESYSTEM scenarios fought entirely underground. These supplementary products are not required to play the adventure, however. TSR 9168

Of all the inhospitable domains in the RAVENLOFT@ campaign world, Bluetspur is the cruelest and most gruesome. Nothing grows in the endless night, and lightning periodically falls like rain. The only place to escape those storms is inside the mind flayers' complex under Mt. Makab, but that is the last place where any sane person would want to go. The High Master Illithid has been hatching black plots by hatching vampiric mind flayers in his laboratories! His prodigies are horribly insane, but if he can complete his plans, he will achieve a new level of dark immortality. A pair of heroes has stolen the key to his success, but they have paid a heavy price for their bravery and are in desperate need of aid unlooked for. Meanwhile, the Lord of the Realm watches over the proceedings and plays havoc with the wits of both sides, sapping strength and will with all-powerful thoughts of darkness. A party of adventurers will need all of their skills to escape this black domain without the loss of life, power, or sanity! Enter now the perpetual twilight realm of Bluetspur, home to mind flayers, a land of relentless nightmares. There's no rest for the wicked or the good in this domain. Once caught within the borders of this desolate land, the characters must complete their mission without delay or lose their minds and become slaves of the Lord of Bluetspur. TSR 9264, from 1992

The Adventurers arrive at a drow outpost in the Underdark. They must either dispose of the drow or ally with them against the invading legions of Orcus!

Save the village of Millvein! Prevent a war with the drow! In this 3-4 hour adventure for 4-5 characters of 2nd level, travel to a small chitine lair to prevent them from destroying the small village of Millvein and inciting a war between the surface and the drow. Includes: A 3-4 hour adventure for 2nd level characters Map of the village of Millvein 2 DM maps Stat blocks for all monsters the players might encounter. See where the adventure began in Into the Underdark - Part 1 A Family Affair The adventure continues in Into the Underdark - Part 3 They Call It A Mine

The final confrontation with the giant, King Snurre, and the entry of mighty adventurers into the caverns under his stronghold (DUNGEON MODULE G3, HALL OF THE FIRE GIANT KING) discovered the Dark Elves, the Drow, had instigated the giant alliance and its warfare upon mankind and its allied races. This module contains background information, a large-scale referee's map with a matching partial map for players, referee's notes, special exploration and encounter pieces, a large map detailing a cavern area, encounter and map matrix keys, and an additional section pertaining to a unique new creature for use with this module and the game as a whole. A complete setting for play of ADVANCED DUNGEONS & DRAGONS is contained herein. This module can be played alone, as the first part of a series of three modules (with SHRINE OF THE KUO-TOA, D2, and VAULT OF THE DROW, D3), or as the fourth part of a continuing series of modules which form a special progressive campaign scenario (DUNGEON MODULES G1, G2, G3, D1, D2, D3, and Q1, (QUEEN OF THE DEMONWEB PITS). TSR 9019

Deep beneath the Isle of Dread, in a place forgotten by the world of light, an ancient, unfathomable evil festers. Within the desiccated ruin known as Golsimorga, the debased kopru servants of Demogorgon work foul rites, steeping immature shadow pearls in pits of liquid insanity. None from the world above have yet fathomed what terrors lurk beneath the Isle of Dread, nor what mad scheme roils to profane life deep within the city's gangrenous corpse. "The Lightless Depths" is the sixth chapter of the Savage Tides Adventure Path, a complete campaign consisting of 12 adventures appearing in Dungeon magazine. For additional aid in running this campaign, check out Dragon magazine's monthly "Savage Tidings" articles, a series that helps players and DMs prepare for and expand upon the campaign. Issue #353 of Dragon features ways to improve the PCs' vessel, the Sea Wyvern, as they take their adventures back to the seas. When the PCs journey deep under the Isle of Dread to find the source of the shadow pearls, they discover horrors beyond imagining in a haunted underground city perched on sanity's razored edge. Pgs. 28-66

In this adventure, the Lord Commander of the Sharn Watch hires the heroes to investigate the murder of an actress. The investigation quickly spirals into a bloody dispute involving a dead wizard’s spell-book, political rivalries, and secrets that might foment war among the Five Nations. Pgs. 1-37

A dwarven expedition has stopped in Mulmaster for much-needed supplies. Furgis Boltsmelter, their founder and leader, is looking for some “no questions asked” protection for the duration of his stay in the city. Whatever he is trying to protect may not stay hidden for long. Can you keep his secret treasure out of the wrong hands? A four-hour adventure for 1st-4th level characters.

In Prisoners of the Drow, a band of adventurers storm a drow outpost, confront the drow mage in charge of it, and rescue prisoners held within. The heroes must bypass traps and devious defenses to reach their goal and accomplish their mission. The adventure is designed for a party of five adventurers between levels nine and twelve. It features: Encounters by Level - Varying types and quantities of creatures are suggested based on the party's actual level, allowing each encounter to present the appropriate challenge to the party. Encounter Notes - Suggestions for how to run combats are provided for game masters who place an emphasis on engaging, tactical battles. Inciting Action - Suggestions for ways to present the adventure to players are provided. Ease of Use - The format and style of the document allows the game master to find information quickly while running the game at the table. Detailed Maps - What's an adventure without maps? Not much else to say here. This adventure is designed as the first in a two-part series. The second adventure Into the City of Spiders takes the adventurers into a drow compound far from the surface. https://www.drivethrurpg.com/product/247674/Into-the-City-of-Spiders

Undermountain: The Caverns of the Many-Legged is an adventure detailing a hidden mini-level for Dungeon of the Mad Mage for characters of levels 12-13. It uses some of the story and lore of that book, but it can be incorporated or dropped into any setting or homebrew campaign. In a hidden part of Undermountain, former slaves feed their fat, monstrous queen who is fixated on revenge. A broken drow house has finally found a place to call home – only to become abominations. And a massive beast slithers, hunting for anything to satiate its hunger and quell its madness. Welcome to the Caverns of the Many-Legged. Which side, if any, will adventurers choose as they explore this hidden mini-level for Dungeon of the Mad Mage? In this adventure, you will find: a mini-level that can be easily incorporated into Dungeon of the Mad Mage a vivid cast of unique monsters and NPCs, including chitine warriors, a choldrith queen, a spellcasting draegloth, a mad yuan-ti anathema, and others (stat blocks provided for all creatures not in the Monster Manual) locations that could be used or adapted elsewhere, such as a chitine colony and a drider-controlled drow fortress a combination of roleplay, exploration, and combat encounters

Part megadungeon, part underground expedition, Operation Unfathomable serves as both a one-shot adventure and a campaign framework. PCs are (optionally) drafted at swordpoint to recover the Nul Rod, a priceless artifact that was recently lost in a local prince's foolhardy attempt to destroy the Chaos Gods of the Underworld. The PCs have been drafted as an expendable set of pawns to venture into the vast and bewildering Underworld and retrieve the Nul Rod. With the Underworld's innumerable beasties being on high alert after the prince's expedition, the PCs must sneak through the incredibly dangerous Underworld. Fighting is not as important as stealth, fast-talking, and running away rapidly. This is the expansion from Sholtis's original Operation Unfathomable, released in Knockspell #5 (2011).

After a drow girl goes missing, characters must delve into the depths of the Underdark to bring her back. As they journey through the dark, characters discover not all monsters are monstrous and webs are capable of restraining all manner of creatures; in fact, they can capture magic itself.

She ran. Where to or for how long, she really couldn't say. The little flame of her oil lamp sputtered and went out a few times. She'd snap her fingers and make the wick flare to life, but she may as well have ran blind. The hallways were pitch black with soot and choked with smoke, every turn was a guess and every corridor a gamble. Unnatural screams echoed from every direction. Left, right, left again, was this the south or north end of the labyrinth? She had no idea. The next turn brought her face to face with a doorway completely consumed in blue fire. The room beyond was so bright she had to look through her fingers at it. A shadow covered her, a shape in the doorway: a hulking creature with a wolf-shaped muzzle and enormous pincers for hands, wreathed in the same blue flames. The screams were getting closer behind her, too. They had her cornered, again. The demon slammed its shoulders through the narrow opening, splintering the wood and stone. She dropped the lantern and let the wand in her sleeve fall into her waiting hand. With a word of power and a gesture, she appeared in the familiar bedroom: stuffy and reeking of wood smoke. She'd have to try again tomorrow, if she could remember. During an exploration on the sixth level of Undermountain, a strange invisible creature leads to a series of collapsed chambers that hide a forgotten secret and one of the most devastating forces known to the multiverse. Marambra Nyghtsteel, the forgotten apprentice of Halaster Blackcloak, has been locked away for an age deep within Undermountain. What point and purpose her forced seclusion has, only Blackcloak may know. When a spell consuming blue fire, known as The Spellplague is trapped within the chambers, a series of events have left Marambra, lost in her madness, struggling to survive.

A powerful new narcotic is making its way through the Spine of the World. Behind it is a secret that could change everything! Explore a lost city and discover the secrets hidden by the gods themselves. (TW: some drug use and the possibility for players to use drugs)

The waters of a sunless sea meet a pebble-strewn shore, beyond which opens a wide Underdark vista shimmering with pale cave-light. Titanic columns as big as castles march miles into the misted distance. The wide, steeply sloping base of the nearest colossal column is carved with streets, walls, and elaborate structures, many with gaping, empty windows. A few glimmer with faint illumination. Are you brave enough to explore the spire-city and face the terrors that lurk within? Part 2 of the Barrow of the Forgotten King series. Followed by Fortress of the Yuan-ti.

A mind flayer has called for a massive conference of monsters in the Underdark beneath Hillsfar. Trolls, umber hulks, demons, and more have answered the illithid's call. To infiltrate this gruesome menagerie, you must embrace the monster within yourself.

Dark Water Trap is a mini-adventure that has a single encounter that involves Duergar using darkness and anti-darkvision to get the player to fall into a Pit trap full of water, so that the party will drown. The encounter either works as a standalone (Ie. the Duergar have been causing trouble), or as a part of a larger adventure or dungeon, Duegar or otherwise. Pgs. 26-27

Are your player's moving out of Velkenvelve? Enjoying a stroll along the shores of the Darklake? On a day trip from Gracklstugh to Neverlight Grove? Sightseeing near Blingdenstone? Then Journey Through the Center of the Underdark is for you. Journey Through the Center of the Underdark contains several detailed encounters ideal for fleshing out traveling days between locations in Out of the Abyss. Furthermore, these encounters could be readily inserted into any 5th Edition Dungeons & Dragons Underdark oriented Forgotten Realms or home campaign setting. Designed for a party of 4-6 fourth through sixth level characters, with easy notes for adjusting encounter difficulties for lower or higher level groups, Journey Through the Center of the Underdark should provide 8-10 hours of exciting in game adventure. Written for your Rage of Demons Out of the Abyss campaign, Journey Through the Center of the Underdark is ideal for any descent into the depths your characters might take. Enjoy!