Waterdeep: Dungeon of the Mad Mage

Undermountain Overview

Undermountain is the largest, deepest dungeon in the Forgotten Realms. This book aims to touch on every major level of that vast, dangerous place.

Waterdeep: Dungeon of the Mad Mage is designed for characters of 5th through 20th level. You can run it as a stand-alone adventure or use it in conjunction with its precursor, Waterdeep: Dragon Heist, which is an adventure that takes characters from 1st level to 5th level.

Running the Adventure

To run this adventure, you need the D&D fifth edition core rulebooks: Player’s Handbook, Dungeon Master’s Guide, and Monster Manual.

The Monster Manual contains stat blocks for most of the creatures found in this adventure. All other necessary stat blocks are included in appendix A. When a creature’s name appears in bold type, that’s a visual cue pointing you to its stat block in appendix A or in the Monster Manual. If a stat block appears in appendix A of this book, the text tells you so.

Spells and equipment mentioned in the adventure are described in the Player’s Handbook. Magic items are described in the Dungeon Master’s Guide or, in the case of new items, the encounters in which they are found.

Area Descriptions

Undermountain is a series of interconnected dungeon levels, each one deeper than the last. Every dungeon level has its own encounter locations keyed to a map.

The adventure text often presents the most important features of a location in the form of a list with boldface headings for ease of reference. These key features are arranged in order of prominence or in the order in which characters are likely to notice them. These summaries are designed to help you process the information at a glance. If a listed feature requires further explanation, you’ll find additional information about that feature after the summary.

Abbreviations

The following abbreviations are used in this product:

| - | - | | hp = hit points | LG = lawful good | | AC = Armor Class | CG = chaotic good | | DC = Difficulty Class | NG = neutral good | | XP = experience points | LN = lawful neutral | | pp = platinum piece(s) | N = neutral | | gp = gold piece(s) | CN = chaotic neutral | | ep = electrum piece(s) | LE = lawful evil | | sp = silver piece(s) | CE = chaotic evil | | cp = copper piece(s) | NE = neutral evil | | NPC = nonplayer character | DM = Dungeon Master |

Character Advancement

The Levels of Undermountain table lists the dungeon’s levels and the character levels for which they’re designed. It’s okay for characters to enter a dungeon level that’s designed for a higher-level party; the encounters there will be more dangerous and taxing, but characters can retreat if things get too rough. Characters can also leave Undermountain, adventure elsewhere, and return to the dungeon once they’re higher in level.

Levels of Undermountain

Each dungeon level contains enough monster XP to ensure that characters who clear out the level can advance to the point where they’re ready to take on the challenges of the next level down. You can also award XP for overcoming traps and for exceptional roleplaying with key NPCs. The Bonus XP Awards table provides recommended XP awards for such interactions.

Bonus XP Awards

Dungeon History

More than one thousand years ago, the wizard Halaster Blackcloak (see appendix A) journeyed from a distant land to the base of Mount Waterdeep, perhaps acceding to the whispered summons of providence. Some believe he hailed from the nearly forgotten empire known as the Cradlelands. In ages past, humanity spread from the Cradlelands across Faerûn, originating from what is now the Plains of Purple Dust, a wasteland birthed out of a conflict with the gods. Others give Halaster less ancient origins, placing him among the early wizards of Netheril, or asserting that he came from a southern nation long since buried by sand and time. Whatever his origin, scholars have recorded that Halaster brought with him seven apprentices to Mount Waterdeep.

With the Seven guarding his back, Halaster tapped into his immense power to summon beings from other planes of existence to help him build a wizard’s tower to dwarf all other wizard’s towers. But as the seasons wore on, the Seven saw less and less of their enigmatic master. Halaster continued to use fell creatures from distant planes for tunneling and other construction beneath his tower, and the wizard kept the nature of most of his underground dealings a secret from the Seven. Eventually, Halaster’s exploration broke into the Underhalls, a complex of tunnels and rooms built by the dwarves around a mithral mine beneath Mount Waterdeep. The architects of the Underhalls, the Melairkyn clan, had long ago been killed or dispersed, and warring duergar and drow had settled in the ruins. Halaster began a crusade against both the drow and the duergar, participating in wild hunts with extraplanar allies through the tunnels. The stubborn duergar dug in until the mithral was largely mined out; then they abandoned the Underhalls, leaving the drow to fight Halaster and his minions alone. The Mad Mage rounded up the remaining dark elves, trapping some of their souls for use in his dark magic, while twisting the bodies and enslaving the minds of others. Once he had wrung the drow of their usefulness, Halaster Blackcloak tunneled on, ever downward, indulging his inexplicable compulsion for delving deeper and deeper into the mountain.

Using his underground complex as a base of operations, Halaster traveled to other planes and distant lands, collecting strange and dangerous creatures to live as prisoners, servants, or guardians in Undermountain. Populating and defending the dungeon became an obsession. Over time, the mage’s preoccupation with Undermountain electrified his eccentricities and infused him with an air of unconcealable madness.

Halaster’s apprentices came and went. Some left only to return—inexplicably drawn down into Undermountain’s depths. Others remained by his side. As they began dedicating more attention to their private obsessions, madness settled into their souls as well.

During the years Halaster quested on other planes and sequestered himself in his tunnels, his magnificent tower and its surrounding walls fell into ruin. In time, the city now known as Waterdeep developed in the shadow of Mount Waterdeep and spread down to the harbor. As the city sprawled outward over the years, it came to surround the ruins of Halaster’s home. Undermountain was known to those early settlers, and they often sent criminals into its endless depths as punishment. So it was for many years, until an intrepid adventurer named Durnan delved into the labyrinth beneath the tower and returned alive, laden with riches and countless harrowing tales. Durnan used his new fortune to demolish the remnants of Halaster’s tower and built an inn over the well he had used to descend into Undermountain, and call it the Yawning Portal. Durnan owns and operates the inn and tavern to this day, serving patrons and inviting the brave and foolish alike to test their mettle in the Dungeon of the Mad Mage.

A Knot in the Weave

Where Waterdeep stands today, there once stood Aelinthaldaar, the capital city of the ancient elven kingdom of Illefarn. When the elves left, they used a powerful spell to erase all traces of their capital. This spell had the unintended side effect of creating a permanent knot in the Weave, the fabric through which all magic is channeled. This knot lies deep underground and isn’t something that can be seen, felt, or undone, but it can cause madness to bloom in the minds of mortal beings who dwell near it for too long. The knot permeates Undermountain, and the madness it causes typically manifests as an obsession with the dungeon itself. Those affected by the knot in the Weave exhibit a subconscious desire to remain in or near the dungeon. Halaster and several of his apprentices fell prey to this obsession, as did many Melairkyn dwarves and Durnan, the proprietor of the Yawning Portal. Not all creatures that dwell in Undermountain succumb to its madness, and those who do aren’t even aware that the dungeon has them in its clutches.

The Yawning Portal

The Yawning Portal, a famous inn and tavern located near the eastern slope of Mount Waterdeep, derives its name from a 40-foot-diameter well that descends into the first level of Undermountain. Located in the center of the taproom, the well was once the outer shell of Halaster’s mighty tower, which was demolished long ago. Its sheer walls are made of old mortared stones. Next to this gaping orifice hangs a winch with a simple rope-and-pulley mechanism that Durnan, the proprietor, uses to lower adventurers down the shaft and (sometimes) pull them up again. Durnan controls the winch himself and will transport only one adventurer at a time. The trip takes 10 rounds, down and up. The rope is stained with old blood and long enough to reach all the way to the floor of the dark room at the bottom of the 140-foot shaft (area level 1, area 1).

Durnan charges adventurers 1 gp each to descend into the well, whether they opt to use the rope or not. The return trip also costs a piece of gold, sent up in a bucket in advance. He also readily accepts coin from patrons who want to place grisly bets on adventurers who dare explore Undermountain, and their odds of returning alive. “Five gold dragons says they’re back before a tenday, minus the fighter, the wizard, and the cleric!” is the flavor of commentary often heard amid gales of drunken laughter.

The walls of the well are crumbly but have abundant handholds and footholds. They can be scaled without climbing gear with a successful DC 15 Strength (Athletics) check. No check is needed to enter Undermountain by using the rope-and-pulley system.

Adventure Hooks

Adventurers who hang around the Yawning Portal often find work delving into Undermountain on the errands of others. The characters might have their own reasons for venturing into the Mad Mage’s dungeon, but the adventure hooks described in this section can be used as further motivation. These hooks are divided into two categories: starting quests and future quests. Adventurers are under no obligation to accept or complete any of these quests, though the promised rewards are often substantial enough to be tempting.

Starting Quests

Starting quests are available to characters from the outset of their experience with Undermountain. Any of the quest givers described below might approach the characters shortly after their arrival at the Yawning Portal. The characters can accept as many or as few starting quests as they want. Based on the needs of your campaign, you might even introduce some starting quests of your own.

Hunt for Magic Items and Spellbooks

Obaya Uday, a neutral good Chultan priest of Waukeen (god of trade), has traveled from the distant city of Port Nyanzaru on behalf of a wizard named Wakanga O’tamu to procure magic items from Waterdeep. When she learned about Undermountain, Obaya booked a room at the Yawning Portal in the hope of hiring adventurers to plunder the dungeon of its magical riches.

Obaya approaches the adventurers and offers to pay for any unwanted magic items they find in Undermountain. Obaya has secured her funds in Waterdavian banks and can pay handsomely within a matter of hours for any magic items the characters bring to her. The amount she’s willing to pay is based on the item’s rarity, as shown in the Magic Item Rewards table, and is nonnegotiable. Characters would be hard-pressed to find anyone willing to spend as much for these items as Obaya is, and she always pays in platinum pieces for ease of transport.

Magic Item Rewards

Obaya is also interested in buying spellbooks for Wakanga O’tamu. She prices a spellbook based on the highest-level spell contained in it: 5 pp for 1st level, 25 pp for 2nd or 3rd level, 100 pp for 4th or 5th level, 250 pp for 6th or 7th level, and 500 pp for 8th or 9th level.

Once she has paid for 7,500 pp worth of magic items and spellbooks, Obaya hires a small squad of bodyguards, books passage on a merchant ship heading to Chult, and returns to Port Nyanzaru with her trove.

Pay a Harper Debt

A lawful good bard named Mattrim Mereg, known as Threestrings to his friends, plays a three-stringed lute at the Yawning Portal and is a much more talented musician than he pretends to be. In truth, Mattrim is a Harper spy who uses this busking gig to establish relationships with the Yawning Portal’s unique clientele.

Mattrim needs a pouch of gold delivered to a female half-drow named Cal’al Claddani, who runs a tavern called the Flagon and the Dragon in Skullport. Cal’al provided shelter and healing to a wounded Harper spy in Skullport and is owed payment for her support. Mattrim’s pouch contains three moonstones worth 50 gp each.

Once they deliver the pouch, characters can take refuge in a Harper hideout called Dalagor’s Fortress, located on the uppermost level of Skullport. Mattrim tells the characters that a dragonborn mage named Felrax guards the place.

Search for Kressando Rosznar

A young noblewoman, Esvele Rosznar has been frequenting the Yawning Portal on busy evenings, keeping mostly to herself while sipping zzar and listening to gossip. Her family has a tarnished reputation, having once been banished from Waterdeep for slavery and other illegal acts. Although the Rosznar family is trying to regain its integrity and standing, several bad apples threaten to impede that progress with their sinister ventures. Esvele’s brother, Kressando, was sent to Skullport to conduct secret meetings with the Xanathar Guild and gauge interest in setting up a slave trade in Skullport, far from the eyes of Waterdavian authorities. Esvele didn’t learn of this meeting until after Kressando vanished, and she is determined to stop his scheming and see him returned to Waterdeep before he can further tarnish the Rosznar name.

Esvele takes one or more of the adventurers aside as they prepare to make their initial descent into Undermountain and asks them to keep an eye out for Kressando, a 22-year-old man with fair skin and dark curly hair, trained in the arts of stealth and thievery. She also tells them that Kressando wears a platinum signet ring bearing the Rosznar family crest (a diving white falcon on a field of blue) and an inscription of the family motto (“Fly high and stoop swift”).

She promises that if the characters can facilitate Kressando’s safe return or deliver proof of his whereabouts to Esvele, she will owe them a favor, adding that “You can trust in House Rosznar.” (For more information on Esvele Rosznar, see Waterdeep: Dragon Heist.)

Characters won’t find Kressando anywhere, but they might find his ring in the possession of a hobgoblin warlord named Azrok (see area level 3, area 21n) and discover how Esvele’s brother met his untimely end. Returning Kressando’s ring to Esvele completes the quest and places her in the party’s debt.

Throne of the Coronal

Volothamp Geddarm, famous explorer and raconteur, offers to buy the adventurers a round of drinks to celebrate their upcoming expedition into the Dungeon of the Mad Mage. Injected into the conversation is the following tale:

This story dates to the fall of Illefarn, an elven kingdom of the North. An alabaster throne belonging to Syglaeth Audark, the last coronal of Illefarn, disappeared from the capital city of Aelinthaldaar, where the Mad Mage built his tower and today stands Waterdeep. It’s said that a group of dwarves feared the destruction of such a miraculous work of stonecraft and stole the throne right out from under the elves' slender noses. Where the dwarves hid it for so long, who knows? But should you find it in Undermountain, it would please the elves of the North to know it survives.

In truth, the ancient alabaster throne was spared the destruction of Aelinthaldaar by Coronal Audark himself, who ordered it placed in an underground vault. Despite the precaution, the throne was damaged in the calamity that befell the elven kingdom. After the fall of Illefarn, Melairkyn dwarves found the throne and bore it to their halls with the intention of repairing it and returning it to the elves.

If the characters find the throne (see area level 3, area 14c) and inform Volo of its location, he shares this information with his elf friends, who express their gratitude by giving the party a beautifully crafted longbow and an elven quiver containing twenty silvered arrows. The bow bears the Elvish inscription “Al hond ebrath, uol tath shantar en tath lalala ol hond ebrath.” This phrase translates to “A true friend, as the trees and the water are true friends.” The elves eventually embark on their own expedition into Undermountain, with the goal of retrieving the throne.

Future Quests

Future quests are available to adventurers only after they satisfy the prerequisites. The characters might need to enter and leave Undermountain several times before they’re eligible to receive these quests.

More of Undermountain to Love

There are vast sections of Undermountain, including hidden levels, beyond those described in this book. Halaster seals off portions of the dungeon that are undergoing construction or reconstruction until such time as they’re ready for exploration. The DMs' Guild (dmsguild.com) is an excellent resource you can use to find and share expansions to Undermountain.

Eye of the Spider

Prerequisite: Complete the “Search for Kressando Rosznar” quest

News of Kressando Rosznar’s death is leaked to the publishers of several local broadsheets, along with the names of the adventurers who retrieved his signet ring from Undermountain. The news inspires Joroth Brighthelm, a dwarf spy for the Lords' Alliance, to visit the Yawning Portal.

Joroth approaches the characters in plain clothes and asks them to keep their eyes open for Falkir’s Fist, a band of four dwarf adventurers that disappeared in Undermountain over a year ago. The leader of the band, Falkir Gravelfist, is believed to have stolen a famous emerald called the Eye of the Spider from the Mirabarran embassy in Waterdeep weeks prior to his disappearance. Joroth believes Falkir is dead (divination spells have confirmed as much) but would like to see the gemstone returned to its proper owners to strengthen political ties between Waterdeep and Mirabar.

Joroth describes Falkir as a particularly stout dwarf wearing a helm shaped like a boar’s head. He says the gemstone is a spherical emerald roughly three inches in diameter, with a small imperfection in its core shaped vaguely like a spider. The gemstone has no magical properties as far as he knows. Joroth offers the friendship of the Lords' Alliance as a reward, which can be useful if one or more of the characters find themselves in need of assistance in Waterdeep or another alliance city. (For more information on the Lords' Alliance and its role in Waterdeep, see Waterdeep: Dragon Heist.)

Characters who belong to the Lords' Alliance gain 3 renown (see “Renown” in chapter 1 of the Dungeon Master’s Guide) for returning the Eye of the Spider to Joroth. Both the gemstone and Falkir’s Fist can be found on level 10.

Retrieve a Runestone Fragment

Prerequisite: 12th level or higher

Volothamp Geddarm introduces the characters to a friend of his: a young captain of the City Watch named Jalester Silvermane. If the characters played through Waterdeep: Dragon Heist, they probably know him already. Jalester is a secret agent of the Lords' Alliance who reports to Lady Laeral Silverhand, the Open Lord of Waterdeep.

Unbeknownst to anyone but her closest confidants, Laeral’s magic has begun to wane. She has researched a way to halt the decline, at least temporarily, but she needs a fragment of a magic crystal called the Runestone. The crystal was created by Halaster Blackcloak and secreted away in the depths of Undermountain. Laeral has sent Jalester to hire a band of adventurers to retrieve a pebble-sized fragment of the Runestone, which he can then deliver to Laeral in utmost secrecy.

Jalester tells the characters that he wants the fragment for himself and won’t disclose its purpose, except to say that its recovery will help to ensure Waterdeep’s security (a true statement). He describes the Runestone as a large, glowing, disk-shaped gem with Halaster’s rune floating in it.

He does not mention a monetary reward for delivering a Runestone fragment to him; instead, Jalester offers the characters his lasting friendship—which can bring many benefits, considering his position in the City Watch. If the characters negotiate for more than Jalester’s goodwill, they’re also promised a luck blade with no wishes remaining. Jalester neglects to mention, however, that this weapon belongs to Mirt the Moneylender, one of the Masked Lords of Waterdeep. Mirt himself delivers the luck blade once the Runestone fragment is in Laeral’s hands, but looks rather put out at the thought of parting with it. “Perhaps you might trade it back for dinner at my mansion?” he asks the characters politely. Allowing Mirt to keep his sword puts the Masked Lord in the characters' debt—a fine prize indeed for their efforts.

The characters can find the Runestone and cast-off fragments of it on level 20 of Undermountain.

Save the Dragon

Prerequisite: Complete the “Throne of the Coronal” or the “Eye of the Spider” quest

Word reaches Lady Wylynd Moonstar, matriarch of the Moonstar noble family of Waterdeep, that a party of adventurers has had some success in Undermountain of late. She learns all she can about these adventurers before sending her grand-nephew, a well-mannered half-drow named Helion Moonstar, to meet with them. Helion is Wylynd’s heir apparent, and this mission is as much a test for him as it is for the adventurers.

Lady Wylynd is well over a hundred years old and senile, but she has never forgotten the dark blemish on her family’s honor left by Vanrak Moonstar, who lorded over House Moonstar long ago. Vanrak and his small army of Shar worshipers fled into Undermountain to escape punishment for their many crimes in the city. It’s Lady Wylynd’s recollection that a longtime ally of the Moonstar family, a bronze dragon named Glyster, was asked or told to find Vanrak and bring him back to Waterdeep to face justice. The dragon found Vanrak but could not wrest him from the depths of Undermountain. Instead, the dragon became corrupted by Shar’s magic and was transformed into a shadow dragon named Umbraxakar. In this evil form, the dragon fought by Vanrak’s side for years, even serving as his mount from time to time.

Lady Wylynd believes it’s her family’s responsibility to free the dragon from Shar’s evil grasp one way or another. She asks Helion to meet with the adventurers and convince them to find the shadow dragon in Vanrakdoom, one of the deeper levels of Undermountain, and break Shar’s hold over him. Failing that, they should put the dragon out of his misery. In exchange for their help, Helion promises the friendship of House Moonstar, which comes with tangible benefits:

• Characters can trade magic items with representatives of House Moonstar, allowing free exchanges of magic items of similar rarity (subject to your approval).
• House Moonstar offers to fund any future expedition the characters decide to mount, providing maps, caravan services, and NPC followers as needed.
• House Moonstar can put the characters in touch with people who can give special training (see “Marks of Prestige” in chapter 7 of the Dungeon Master’s Guide).

Uncover the Telepathic Spy

Prerequisite: 9th level or higher

An ulitharid (see appendix A) has been using telepathy to contact random people in the city and learn all it can about Waterdeep. Those the creature has contacted know nothing of the ulitharid’s true nature, only that an alien intellect has reached out to them for information. Word of these telepathic intrusions has begun to spread throughout the city, gaining traction as more than just a mad rumor. Several of Durnan’s regular patrons have spoken at length about it, and Durnan believes the source might be somewhere in Undermountain. In fact, he thinks a horrific, psionic monster called an elder brain might be lurking in the dungeon. Not wanting to alarm anyone with rumors of mind flayers, he keeps this conjecture to himself for now.

Durnan urges adventurers to find the source of the telepathic contact, learn its intentions, and put a quick and decisive end to it if those intentions are hostile. (The ulitharid awaits them on level 17.) If the party deals with the threat, Durnan promises to make sure the deed is never forgotten but offers no tangible reward.

Undermountain Secrets

Appendix C of this book contains the Secrets Deck—paper cards for you to photocopy and hand out to the players when their characters learn reliable information about Halaster and Undermountain.

Any character who spends at least four hours in the Yawning Portal is likely to overhear tall tales about the Mad Mage and his dungeon. Not all rumors are to be believed, however, and characters need keen ears and sharp insight to determine which stories have weight. Have each character make a DC 20 Intelligence (Investigation) check or Wisdom (Insight) check. If the check succeeds, the character learns a secret about Undermountain, and the player can draw a card from the Secrets Deck.

Players can hold onto these cards for later reference. When the characters meet an NPC in Undermountain who knows a fact, have one of the players draw another card from the Secrets Deck to determine what that NPC knows about Halaster and his dungeon.

Jhesiyra Kestellharp

Among the greatest of Undermountain’s secrets is the story of Jhesiyra Kestellharp, who was one of Halaster’s most gifted apprentices until it became clear to her that Halaster was irrevocably insane. She fled, but Halaster dragged her back to Undermountain and trapped her in the Citadel of the Bloody Hand, a dungeon complex under Mount Waterdeep connected to Undermountain. Jhesiyra escaped her prison when its wards failed during the Spellplague. To hide from Halaster, she magically confined herself in the stones of Undermountain. She now exists in a bodiless state, inhabiting the very dungeon itself. Halaster is unaware of Jhesiyra’s presence but also wonders over her disappearance following the Spellplague.

Jhesiyra’s plan is to use adventurers to defeat Halaster so that she can seize control of Undermountain. To that end, she does everything in her power to keep adventurers in Undermountain alive. Her abilities are, however, limited in her current, bodiless form.

Jhesiyra can exert control over Halaster’s magic gates, keeping adventurers from passing through them if she thinks they lack the might needed to defeat the perils beyond. In terms of game rules, characters are prevented from passing through a gate when their experience level fails to meet a prerequisite (the recommended character level for which the dungeon level is designed). Any character who doesn’t qualify is pushed back without being harmed when trying to step through the open gate. Only a wish spell can allow a character to pass through. As the Dungeon Master, you can suspend this restriction and allow characters who don’t meet the level prerequisite to pass through a gate, particularly if you think they have the resources to survive and overcome that dangers that await them.

Jhesiyra can’t stop characters from moving between dungeon levels by more conventional means. Whenever they enter a dungeon level designed for characters of a higher experience level, Jhesiyra sends them the following telepathic warning in Common: “Turn back! You’re not prepared for the danger that lies ahead!” Characters are free to ignore her warning. She can’t and won’t elaborate on the nature of the danger that awaits the adventurers or communicate with them in any other way, for fear of being detected by Halaster.

Powerful divination magic can reveal Jhesiyra’s disembodied presence throughout Undermountain. But not even a wish spell or divine intervention will allow direct, two-way communication with Halaster’s former apprentice.

Dungeon Features

For the sake of avoiding repetitive descriptions, common features of Undermountain are summarized here.

Alterations to Magic

Halaster doesn’t make it easy for creatures to enter or leave his dungeon. No spell other than wish can be used to enter Undermountain, leave it, or transport oneself from one level to another. Astral projection, teleport, plane shift, word of recall, and similar spells cast for these reasons simply fail, as do effects that banish a creature to another plane of existence. These restrictions apply to magic items and artifacts that have properties that transport or banish creatures to other planes as well. Magic that allows transit to the Border Ethereal, such as the etherealness spell, is the exception to this rule. A creature that enters the Border Ethereal from Undermountain is pulled back into the dungeon upon leaving that plane.

Magic that summons creatures or objects from other planes functions normally in Undermountain, as does magic that involves an extradimensional space. Any spells cast within such an extradimensional space (such as that created by a Mordenkainen’s magnificent mansion spell) are subject to the same restrictions as magic cast in Undermountain.

Spells can’t destroy or alter the shape of Undermountain’s magically protected ceilings, pillars, columns, walls, or floors. For example, an earthquake spell would not trigger a ceiling collapse or create fissures in Undermountain. Doors and furnishings, however, are not protected in this way.

While they are in Undermountain, characters who receive spells from deities or otherworldly patrons continue to do so. In addition, spells that allow contact with beings from other planes function normally.

Sending Spells

Inside Undermountain, Halaster can’t be contacted by means of sending spells. Any creature that tries to contact him with a sending spell is magically redirected to the Mad Mage’s nothic secretary (see area level 9, area 31). Each time it is contacted in this manner, the nothic replies with a string of expletives in Undercommon. Other things the nothic might say (in Undercommon) include the following:

• “Are you alive or just waiting to be conjured?”
• “Get out of my extradimensional space!”
• “There’s a knot in the Weave! I can’t untie it!”
• “Halaster’s not home right now.”

Halaster’s Goals

The Mad Mage makes his presence known throughout this adventure. Most often, he’s a distant observer, watching with amusement as adventurers contend with the denizens and other dangers of his dungeon. Other times, he appears before them in the form of a spectral eye or some other magical force. Why does he tolerate adventurers in his home? What’s his aim? That’s for you to decide. This sidebar outlines several possible goals for Halaster. Choose one you like, or randomly determine Halaster’s goal by rolling a d6. His goal can change at any time without explanation; he is the Mad Mage, after all.

Goal 1: Clean House: Halaster wants adventurers to clear out parts of his dungeon so that he can restock the tunnels with new threats from across the planes. He’s unhappy about the amount of space the drow take up on levels 3, 10, and 12. He’s also concerned that the conflict between the githyanki on level 16 and the mind flayers on level 17 could spiral out of control; consequently, he wants one side or the other (or both) eliminated.

Goal 2: Destroy Ezzat: An irksome lich named Ezzat has taken refuge on level 20, and Halaster wants adventurers to destroy the lich and its phylactery. Halaster has bound two genies (a dao and a marid) to level 19 and uses them to help adventurers accomplish this goal.

Goal 3: Strike Fear into Heroes' Hearts: Halaster wants fewer adventurers coming down the well to pester him and steal his valuable belongings. To that end, his goal is to terrify adventurers and send them screaming back to Waterdeep with horror stories that discourage others from descending into Undermountain.

Goal 4: Become Waterdeep’s Shadow Lord: The Shadowdusks were Waterdavian nobles who descended into madness, taking refuge in Undermountain. Halaster wants to return them to power in the city above and use them as puppets to rule Waterdeep from below as its Shadow Lord. Adventurers can thwart Halaster’s scheme by destroying the leaders of the Shadowdusk family and laying waste to their stronghold on level 22.

Goal 5: Find an Apprentice: Halaster is searching for one or more new apprentices worthy of his time and tutelage. He is cultivating talent on level 9, but he’s also paying close attention to other arcane spellcasters who enter Undermountain. Of course, once the novelty of new apprentices wears off, Halaster will likely do the same thing he’s done with all his previous apprentices: teach them ways to mutilate and destroy themselves.

Goal 6: Locate Jhesiyra: Somewhere in the back of his twisted, paranoid mind, Halaster believes that Jhesiyra Kestellharp is still alive and plotting to destroy him. He has no clue where Jhesiyra might be, but he can’t rest until the mystery of her disappearance is solved and she’s his prisoner once again. Halaster thinks he can use the adventurers to lure Jhesiyra out of hiding, but they turn out to be the same adventurers she’s using to find and destroy him.

Architecture

Undermountain is made up of a mixture of smooth, worked stone and rough-hewn stone, with the occasional intruding natural tunnel or cavern. A few levels have exceptional architectural features; for example, level 16, the Crystal Labyrinth, has walls, floors, and ceilings made of crystal.

Ceilings

It’s helpful to know the height of a ceiling, particularly if creatures in the area can climb or fly.

Rooms

A room’s ceiling is at least as high as the room is wide, often higher. If a room’s ceiling height isn’t specified in the text, assume it’s the minimum height.

Tunnels

A tunnel’s ceiling is as high as the tunnel is wide, unless otherwise noted. Most tunnels in Undermountain are arched and have no visible structural supports. Exceptions are called out in the text.

Doors and Secret Doors

Normal doors (including double doors) are made of thick, sturdy wood fitted with iron hinges and handles, and protected against moisture by magic. Secret doors are fashioned of the same material as the surface in which they’re set (usually stone) and require a successful DC 20 Wisdom (Perception) check to locate, unless noted otherwise. When they are closed, most doors and secret doors create airtight seals, keeping gases and gaseous creatures from passing through them; exceptions are noted in the text.

A one-way door can be manually opened only from one side (the other side has no handle or hinges). A knock spell or similar magic is needed to open a one-way door from the “wrong” side.

Not many doors in Undermountain have locks, but those that do sport locks of masterful craftsmanship. When confronted by a locked door, a character with thieves' tools can pick the lock with a successful DC 20 Dexterity check.

A locked or stuck door can be forced open with a successful DC 20 Strength (Athletics) check. A creature that fails a check to force open a door can’t make another attempt on the same door unless it has another creature or a tool (such as a crowbar) to assist.

If the direction in which a door opens becomes important, decide for yourself which area the door opens into.

Expanding Undermountain

Each dungeon level has tunnels that lead off the edge of the map. These tunnels can be ignored if you have no desire to expand the dungeon. If you choose to expand a level by creating new rooms of your own, you can attach your section of the dungeon to an existing map by using one of these connecting tunnels.

Elder Runes

Elder runes are ancient symbols imbued with magical power. With years of study, any creature that can cast the symbol spell can learn an elder rune and add it to the selection of symbols that can be created with the spell. Halaster has spent lifetimes studying elder runes, inventing new ones, and harnessing their volatile magic. He likes to place them throughout Undermountain as hazards.

Appendix B presents several elder runes on paper cards that you can photocopy and cut out to create an Elder Runes Deck. When circumstances call for the appearance of an elder rune, a card is drawn from this deck to determine which rune appears and what it does.

Elder runes function as symbols cast using the symbol spell, with these changes:

• An elder rune has two possible effects: one beneficial (called the boon effect) and the other harmful (called the bane effect). The elder rune’s creator chooses which effect occurs or can randomize it so that a die is rolled to determine whether the bane effect (odd die roll) or the boon effect (even die roll) is triggered.
• A triggered elder rune targets one or more creatures within 60 feet of it, according to the caster’s specifications. Once the effect activates, the elder rune disappears and the spell ends.

A creature doesn’t make a saving throw against an elder rune’s boon effect. Saving throws made to resist the bane effect of Halaster’s elder rune have a spell save DC of 22.

Gates

Halaster creates magic gates that allow instant travel between levels of the dungeon. He can also create gates that lead into and out of Undermountain, which he uses primarily to restock the dungeon with monsters. His old gates were destroyed by the Spellplague, but Halaster has replaced them with new ones, most of which have destinations confined to the dungeon. These gates are not subject to the restrictions outlined in the “Alterations to Magic” section.

Opening a gate in Undermountain usually requires a special key, the casting of a spell, or some other act. Halaster likes to leave clues to help adventurers solve each gate. A legend lore spell or similar magic can also reveal the proper way to open a gate.

An open gate acts as a two-way portal and typically remains open for 1 minute upon activation. Creatures peering through the open gate can see the destination beyond as though they are looking through an open doorway into that location.

A gate can’t open within the area of an antimagic field spell or similar effect. Dispel magic has no effect on a gate, but a wish spell can permanently destroy a gate or force it open for up to 1 hour. A gate cannot be damaged or destroyed otherwise.

Halaster favors three kinds of gates:

• Arch Gate. This gate looks like an archway chiseled into a blank wall. The archway is 10 feet high and 10 feet wide unless otherwise noted. Most of the gates in Undermountain are arch gates.
• Mirror Gate. This gate consists of a wall-mounted mirror, ovoid or rectangular, encased in a carved stone frame. The mirror is 10 feet tall and 5 feet wide unless otherwise noted. All the gates leading to and from level 10 are mirror gates.
• Standing Gate. This gate forms between two standing stones or pillars. Unless otherwise noted, these columns are 15 feet tall and spaced 10 feet apart, with a stone lintel resting horizontally atop them to form a rectangular opening. Because the gate is freestanding, one can pass through it from either direction.

Elder Runes on Gates

When a gate opens, a random elder rune appears within its vertical plane. Draw a card from the Elder Runes Deck to determine which rune appears. Halaster usually has the rune target the first creature that passes through the open gate. Every so often, to keep the players guessing, you can have the rune trigger when the second or third creature passes through. Once an elder rune is triggered, it vanishes until Halaster recasts the symbol spell on the gate.

Illumination

Since the creatures that originally carved out Undermountain had darkvision and Halaster lights his way by using magic, areas of the dungeon are unlit unless otherwise noted.

A Visit to Alterdeep

If your party of adventurers is incapacitated or killed in Undermountain, you have an unusual option for keeping both them and the campaign alive: the characters could awaken in an alternate version of the Yawning Portal that is part of a psionically generated simulation of Waterdeep called Alterdeep, created by the ulitharid on level 17. If you choose this option, the characters are stabilized, brought to level 17 of the dungeon by mind flayers or their thralls, and placed in capsules called psipods. While unconscious and trapped in these psipods, the characters are immersed in the ulitharid’s realistic simulation of Waterdeep. Over time, they’ll notice inconsistencies that suggest they’re not where they appear to be, and they’ll have chances to converse with the ulitharid in its many guises and convince it to set them free. For more information on Alterdeep and its ulitharid creator, see level 17.