An Introduction

Return to Undermountain
An Introduction
By Matthew Sernett

Undermountain? Ah, yes. A great place to have fun, the most famous battlefield in which to earn a reputation as
a veteran adventurer -- and the largest known mass grave in Faerûn today.

-- Elminster of Shadowdale

Undermountain, that seemingly endless dungeon beneath Waterdeep --

mentioned in countless Forgotten Realms products, detailed in two boxed
sets and several adventures, and so vast that such efforts barely scratched
the surface of its many miles of corridors and acres of rooms -- remains
one of the most recognizable locations in Faerûn. Often called the
"deepest dungeon of them all," Undermountain has tempted countless
adventurers to delve into its depths. Some return with tales of its horrors.
Most are never seen again. Yet enough of those few who return come
back with astounding wealth to entice others to follow suit and take the
chance that the halls beneath the mountain become their tomb.

This article series details some of the rooms and halls of Undermountain
so that you can use them in your game. As with the many Undermountain
products of the past, this series of articles cannot hope to detail every room
and corridor of the vast dungeon beneath Waterdeep. Instead, it will detail
individual rooms and encounters that you can use when you run
adventurers through Undermountain or any dungeon of your own devising.

TSR published The Ruins of Undermountain, the original boxed set describing the first three levels, in 1991. A
few things have changed since then. Fans of the old dungeon description will find some new encounters,
recognize some old favorites, and be surprised by some new twists. For those new to Undermountain, this
introduction acts as a primer, telling you what you need to know to imperil PCs' lives in the Forgotten Realms
setting's most famous dungeon.

How to Use Undermountain

This articles series presents the map of the first level of Undermountain and describes a few rooms within it each
month. These dungeon rooms share Undermountain as a linking theme, but you can easily take them out of this
context and place them into any adventure of your making. If you want to use Undermountain as a setting for
your PCs' adventures beneath Waterdeep, don't wait for all the articles before you get started. You can use the
map and the first few rooms as a starting point for adventures you devise, and if a future room description
contradicts your version, you can incorporate the room in another part of the dungeon or have the room change
to fit the new description, presenting a surprise to your players.

A Short History of Undermountain

 An Introduction

Over a thousand years ago, the wizard Halaster Blackcloak whirled to the base of Mount Waterdeep, called there
from a distant country by chance or providence. Some say he hailed from the Cradlelands, the nearly forgotten
empire that spread humanity across Faerûn and Kara-Tur from what is now the Plains of Purple Dust, a
wasteland created by conflict with the gods. Whatever his origins, scholars record that Halaster brought with him
the Seven, as his apprentices are known, and with their help and his power, Halaster summoned beings from
other planes to build himself a wizard's tower. Halaster ringed his tower with a great wall set with lesser towers
for each of his apprentices, and he created fields and farms to be worked by his apprentices and their servants.

For a time, it seemed a good life for the Seven, but as the days wore on, they saw less and less of their dread
master. Halaster continued to use fell creatures from other planes for construction beneath his tower, and he
kept his dealings with them and the nature of the tunnels from the Seven. At length, Halaster's tunneling broke
into the Underhalls, a complex of tunnels built by dwarves around a mithral mine beneath Mount Waterdeep. The
dwarves who built the dungeons, the Melairkyn clan, had long ago been killed or dispersed, replaced by oft-times
warring duergar and drow. Halaster began a crusade against both races, participating in wild hunts through the
tunnels with allies called from the Outer Planes. The duergar stubbornly remained until the mithral was largely
mined out, but then they left the drow to fight Halaster and his minions alone. Halaster captured or killed the
remaining dark elves, entrapping their souls for dark magic or twisting their bodies and enslaving their minds.
When the last of the drow were defeated, Halaster Blackcloak tunneled on, ever downward, continuing his
strange obsession with delving beneath the mountain.

Finally, when Halaster was absent for more than a year, some of his apprentices ventured into his tower in
search of the great wizard. They found traps, monsters, and tantalizing hints about power beneath the earth.
Individually they plumbed the depths of the dungeons, encountering evermore-deadly traps and more powerful
foes. For their efforts, they were rewarded with riches and magic. When the Seven were reduced to five, Halaster
appeared to his students and explained that he had built the tunnels to guard his experiments and treasures. He
enlisted their aid to make his dungeons even more secure.

What happened after that is unclear, but only one apprentice is known to have left Undermountain, and she fled
the area, never to return. Halaster continued to live beneath the mountain, using it as a base from which he
traveled to other planes and distant lands, entrapping strange creatures and bringing them back to live as
prisoners or guardians in his home. In time, Halaster sought out magic to extend his life, and some say that it
was these spells and items that finally drove Halaster beyond all reason. While before he had been obsessed
and deranged, his quest for immortality seemed to drive him truly mad.

While Halaster quested on other planes and sequestered himself in his tunnels, his tower fell into ruin. When
Halaster was yet active in the outside world, his home was considered an accursed place, so settlers in the area
largely left the crumbling tower alone. In time, the city now known as Waterdeep came to huddle against the
mountain and reach down to the harbor. As the city sprawled outward, it reached and encompassed the ruins of
Halaster's home. Undermountain was known to these early settlers, and they often punished criminals by
sending them into its depths. So it was for many years until an adventurer named Durnan delved into the depths
beneath the tower and returned, laden with riches, to tell the tale. Durnan demolished the last remnants of
Halaster's above-ground abode and built an inn over the well he had used to descend into the depths. He called
his inn the Yawning Portal, and Durnan works there to this day, serving patrons and inviting the brave or the
foolish to try their hands at the halls of Undermountain.

Reasons to Enter Undermountain

 An Introduction

If riches and power aren't enough to entice your players' PCs to try their luck in Undermountain, there exist
countless other options to get them involved. Presented below are a few ideas for how to get their adventures
beneath Waterdeep started.

● A nobleman ventured into Undermountain and has been gone for a week. Divinations revealed he is alive
and held captive in the dungeon complex, but attempts to divine his exact location have failed. His house
offers a tremendous reward for someone to rescue him.

● One of the PCs' long-time foes ventures into Undermountain along with a captive, magic item, or holy
relic important to the PCs. Their only hope of regaining what they've lost is to follow.

● If the PCs rack up a great debt, someone might call in that debt and offer Undermountain as a means of
quickly gaining enough for payment.

● Other adventurers challenge the PCs to enter Undermountain with them, betting their takings from the
dunegons against the PCs' with the group who amassed the most taking all. If the PCs refuse, the other
adventurers call them cowards, and their bard makes up some catchy tunes about the party's lack of
courage.

● If the PCs run into trouble with the law or with a criminal organization, they might be sent into
Undermountain as punishment. Capital punishments are sometimes commuted to just such a penalty.

Ways In and Out

Many ways lead into Undermountain and few ways lead out. Many seeming exits just lead farther into the maze,
and many traps dump their victims in deeper levels of the dungeon. A future article might detail some of the
many exits and entrances to Faerûn's largest mass grave, but this series assumes the PCs enter and exit by
one: the well at the Yawning Portal Inn.

The Yawning Portal

The Yawning Portal, famous for holding the entrance to Undermountain, stands in Waterdeep on Rainrun Street
in the upper part of the Dock Ward. It's a must-see location for many visitors to the great city, and many
adventurers use it as their starting point and refuge during their dungeon plumbing.

Built on the site of Halaster's tower, the Yawning Portal is a rambling structure strewn with blue tapestries. Food
at the inn is decent and prices for room and board are fair. Durnan (NG male Ftr18) built the Yawning Portal with
wealth taken from the Undermountain, and he has run the inn since his retirement from adventuring more than
seventy years ago. Now approaching a hundred years of age, the white-haired Durnan is nevertheless a
powerful presence behind the bar, and many consider him an institution in Waterdeep. With muscles like catapult
shots and a greatsword hung among the racks of mugs and bottles, few make trouble in the inn, and those who
do quickly come to regret it. The local toughs and bravos know better than to set foot in the Yawning Portal, and
newcomers to the inn receive a friendly welcome from other patrons along with an admonishment about fighting
or casting spells. Durnan asks those who do come to conflict to leave the inn, ejecting them if they refuse. A few
off-duty city guards are usually in the taproom, and they call on their fellows to arrest any brawlers, whether
inside or outside. As a result of Durnan's influence and the attraction of the entrance to the dungeon, having
dinner or a drink at the Yawning Portal remains a relatively safe and entertaining way to spend time, and many
local laborers and merchants rub shoulders with the exotic foreigners and adventurers drawn to the place.
 An Introduction

The centerpiece of the taproom is a wide well with a low wall. This is the "yawning portal" and the entrance to
Undermountain. The well is surrounded by everburning torches, and a large winch-and-pulley construction hangs
a rope over a 140-foot drop into the dungeon. Entrance to Undermountain costs 1 gp. Durnan happily lowers any
paying patron into the well by means of the winch and a long length of silk rope. Durnan doesn't like lowering
more than one person on the rope at a time, although he'll make exceptions for Small characters and
exceptionally light individuals. If someone insists on being lowered with more weight than Durnan thinks the rope
can hold, the innkeeper asks that the party pay for a replacement for the rope in advance, and should it break on
the way down, Durnan hollers an "I told you so" to the falling adventurer -- much to the amusement of his
patrons. Those who make use of the well without paying earn Durnan's ire, and he refuses to raise them out of
the well without having them first tie their wealth and gear -- everything but underclothes -- to the rope. Durnan
then keeps the wealth and holds the gear and items until the adventurer can afford to buy them back at a fair
price or pay 1,000 gp, whichever is less.

If an adventurer returns to the well and wants to come back up, he must have 1 gp to pay Durnan. Those who
can't pay must give Durnan their gear, paying Durnan 500 gp or the cost of their gear before he returns the
items. If someone refuses Durnan's terms or attempts to leave without paying, Durnan either leaves them at the
bottom of the well or forcibly puts them back down there. The 140-foot drop convinces most folk that
embarrassment and poverty is the preferable option.

Durnan provides other services to adventurers. In addition to providing food and libation, he rents rooms and
storage lockers, and he keeps some dungeoneering essentials on hand to sell to those who might have forgotten
something in their preparations. Use the prices for equipment, edibles, and inn stays as provided in the Player's
Handbook. Durnan charges 5 gp a day for use of a storage locker, and he requires payment up front. He sells
the items stored within if a person doesn't return to take them. This might seem steep, but few safer places exist
within the city to store wealth and goods than with Durnan. Durnan also sells healing potions provided to him
through the temple of Tymora in the city. He charges the price in the Dungeon Master's Guide since he buys
them in bulk at a discount. Durnan doesn't provide other healing or help to returning adventurers, but he'll send a
runner with a message to one of the temples for free. (He considers such a small service to be paid for by the
PCs' entrance fee and the entertainment they provide to his patrons simply by choosing to delve into the
dungeons.)

When adventurers pay to enter the well, patrons cheer, share rounds of drinks, and generally give the heroes a
grand going-away party. For those not distracted by the celebration, the scene might seem a bit grisly as
customers at the inn and those working there openly bet on whether or not the adventurers will return, in what
state they'll return, and how many might come back. Adventurers are not allowed to participate in this betting.

The Powers of Halaster

Halaster (male human Wiz25/Acm5, detailed in the Forgotten Realms Campaign Setting and updated in Epic
Level Handbook) still roams the halls of Undermountain and views them from a secret base unreachable from
the dungeon's tunnels. In past products, Halaster's influence provided an explanation for traps resetting,
monsters being replaced, and to obstruct the use of certain types of magic. You can use Halaster's powers in a
similar manner, but such things can be frustrating to players, so employ such tactics with caution.

These articles assume that Halaster's influence is felt in just one manner: a teleport cage (see City of Splendors:
Waterdeep, to be released in July, for a spell description) that encompasses all of Undermountain. When a
conjuration (teleportation) spell is cast within Undermountain, the spell transports all affected creatures and
objects to another random location within Undermountain. When a caster outside Undermountain attempts to
teleport into it, the effect redirects their destination to another random location reachable by the spell. For
 An Introduction

example, if a 9th-level wizard in Waterdeep attempted to teleport into the depths of Undermountain, the teleport
cage would cause him to appear at another random location within 900 miles of the place where he cast the
spell. This effect is well known, and Durnan warns adventurers of it before winching them down.

Here are some other possibilities for Halaster's influence that might make adventures in Undermountain unique.

● Spells that alter the dungeon, such as passwall or stoneshape, fail or go wild.

● Divination magic of various types, such as scrying and magic that locates objects or creatures, fails or
goes wild.

● The whole dungeon might radiate powerful obscuring magic, making detect magic useless as a means of
discovering magic traps.

● Traps reset after a designated a period of time.

● Portals open at random, sometimes depositing monsters in rooms thought to be empty.

Dungeon Features

This section describes assumptions about the features of Undermountain. See the Undermountain Cheat Sheet
sidebar for statistics you might like to keep handy when running adventurers through one of the rooms described
in this series of articles.

Map Squares: Note that squares on the large Undermountain map represent 10-foot squares, just as they did in
the original Ruins of Undermountain boxed set. In the maps of each room that accompany the articles, squares
represent normal 5-foot squares.

Climate: The temperature in the dungeons tends to be a little chilly, but dungeon delvers don't require more than
typical adventuring garb. Parts of the dungeon are dank and moldy while others are dry and dusty. Some parts of
Undermountain vary greatly from the norm, and in such cases, the room description will note this. Many sources
of fresh air lead into the various levels of Undermountain, and unless otherwise noted, the air in the dungeons is
clean apart from occasional dustiness or dampness.

Ceilings: Unless otherwise noted, ceilings in rooms are 10 feet above the floor. Although once constructed of
smooth stone, most ceilings bear the cracks and pock mocks from centuries of age and countless battles. Unless
otherwise noted, PCs can climb ceilings (hanging from hands) with a DC 25 climb check.

Floors: Most floors in Undermountain rooms consist of relatively smooth stone or flagstones. Neither floor type
requires special rules for movement.

Floors in caverns should be considered hewn stone floors. A character running or charging on a hewn stone floor
must make a DC 10 Balance check or be unable to run or charge (the character can still act normally).

Other floor types exist in Undermountain, and when necessary, their description will appear in the description of
a room. For more information on floors, see page 60 of the Dungeon Master's Guide.

Walls: Halaster and the dwarves and drow before him constructed Undermountain of walls of superior masonry.
 An Introduction

Cavern walls are typically unworked. Both have a Climb DC of 20, 15 hit points per inch of thickness, and a
hardness of 8.

Thin walls between rooms are 1 foot thick and have 90 hit points (half normal) because they lack the support of
bedrock behind them.

Doors: Unless otherwise noted, doors in Undermountain are 4 inches thick, 5 feet wide, and made of stone.
They sit and hang on pins on one side, usually the left side if one pushes the door open. Doors open into rooms
from hallways, and into smaller rooms from larger ones, as a rule of thumb.

Stone doors have hardness 8, 60 hit points, and a break DC of 28 whether stuck or locked. All doors have built-in
good locks (DC 30 Open Lock check to lock or unlock), but keys are largely missing, and locks are often broken.
Unless other wise noted, doors are not locked or barred.

For more information about dungeon doors, see page 60 of the Dungeon Master's Guide. For more information
about locks, see page 61.

Doors line up with a 5-foot square even though the main Undermountain map indicates they would straddle a line
between squares.

Secret Doors: In general, secret doors consist of stone made to Undermountain Cheat Sheet
blend in with the surrounding walls. The typical secret door can
be found with a DC 20 Search check, and it might or might not
Here are some statistics you might find
have a lock or even be opened from the side the PCs stand on.
handy as you run the encounters described
Remember that dwarves receive a free Search check to note
in these articles.
unusual stonework, and elves get a free Search check to find
secret or concealed doors.
Door (Stone): 60 hp (hardness 8); Break DC
Secret doors line up with a 5-foot square even though the main 28 (stuck or locked).
Undermountain map indicates they would straddle a line between
squares. Secret Door (Stone): Search DC 20; 60 hp
(hardness 8); Break DC 28 (stuck or locked).
Light and Darkness: Most of Undermountain remains unlit by
any light source, but some rooms and halls might be lit by Lock (Good): 30 hp (hardness 15); Open
ancient magic or recent inhabitants. Room descriptions assume Lock DC 30. Note that locks built into
the PCs can see about 60 feet in darkness, so be sure to modify dungeon doors cannot be attacked
your description of the room if the PCs can see a shorter or separately from the door.
farther distance in the dark. Also, recall that darkvision is in black
and white. Floor (Room): No special rules unless
otherwise noted.
Listen Checks: Remember that PCs passing near a door, secret
door, or hall to a room with some activity in it might have an Floor (Cavern): DC 10 Balance check to
opportunity to hear what's happening on the other side. Similarly, charge or run.
creatures in distant rooms or passages have a chance to hear
the PCs. See page 78 of the Player's Handbook for modifiers to
Listen checks. Ceiling (Room): DC 25 Climb check.

Spot Checks: Spot checks function normally in Undermountain, Ceiling (Cavern): DC 25 Climb check; DC
 An Introduction

but remember that PCs can see only as far as their light sources increases by +5 if surface is slippery.
reveal or their darkvision allows.
Wall (Room): Hit points vary based on
Random Encounters: A future article might detail random thickness (hardness 8); Climb DC 20. If the
encounters particular to Undermountain, but for now, use the wall is a thin wall (1 foot thick) between
rules presented in the Dungeon Master's Guide on page 78. You rooms: 90 hp (hardness 8); Break 35, Climb
can roll for a random encounter as often as you like, but keep in DC 20.
mind the party's condition and how the number of random
encounters can affect how populated the dungeon seems to be. Wall (Cavern): Hit points vary based on
thickness (hardness 8); Climb DC 20.
Telportation: Conjuration (teleportation) spells transport all
affected creatures and objects to another random location within
Undermountain. When a caster outside Undermountain attempts to teleport into it, the effect redirects their
destination to another random location reachable by the spell.

Traps: Traps of endless variety litter Undermountain's halls and rooms. Some traps exist merely to move
dungeon delvers deeper into the dungeon or to get them lost. A future article might detail traps in
Undermountain; for now, use the traps described in the Dungeon Master's Guide. When using traps, keep in
mind their effect on the pace of the game; one hidden pit or arrow trap can cause the PCs to slow to a crawl as
they check every step for hidden danger.

The Map

This poster map of the Ruins of Undermountain measures approximately 30"x22" and can be printed on one
sheet of paper on a large-format printer or as individual 8.5"x11" sheets that you assemble. Wizards of the
Coast, Inc. grants permission to use these images for personal use only.

Poster Map Instructions

The full-sized map of Ruins of Undermountain is

approximately 32"x20" and is available in two
formats.

30"x22" Format

This is one large file for printing to a large-format Piece 1 Piece 2 Piece 3
printer. It can also be used by programs that are
capable of "tile printing" to break the map up into
sizes that are appropriate for your situation.

● Ruins of Undermountain Poster Map as one

large 30"x22" file (13.2mb ZIP/JPG)

8.5"x11" Format
Piece 4 Piece 5 Piece 6
This format has the single large map broken into
nine 8.5"x11" sections for printing on a typical home
 An Introduction

printer, then assembling into the large poster size.

This visual guide shows you which image represents
which area of the map.

● Ruins of Undermountain Poster Map Pieces

as a single download (6.9mb ZIP/JPG)

Future Articles
Piece 7 Piece 8 Piece 9
In addition to dungeon rooms and encounters, future articles might detail random encounters, traps, and
dungeon dressings particular to Undermountain. For now, use Tables 3-18 through 3-21 beginning on page 78 of
the Dungeon Master's Guide.

Better Adventures in Undermountain

Several products will make your adventures in Undermountain more fun and more detailed. Check out the
following books for excellent ideas and great inspiration to add depth and detail to your PCs' dungeon delvings.

Forgotten Realms Campaign Setting: In addition to describing Waterdeep and the surrounding area, this book
contains NPC statistics for Halaster and a few other noteworthy characters who might be met in Undermountain.

Epic Level Handbook: This book contains updated statistics for Halaster Blackcloak.

City of Splendors: Waterdeep: To be published in July, City of Splendors: Waterdeep details the city above
Undermountain and describes the history of Undermountain and surrounding area in great detail. It's the perfect
resource for a campaign in the great dungeon, and using it is an excellent way to have both city adventures and
dungeon crawls at your fingertips.

Underdark:Underdark describes the inhabitants that dwell in the Underdark near Undermountain as well as
giving great descriptions and advice for spelunking adventures.

Dungeon Master's Guide II: Chapters in this book include advice about running a game and designing
adventures. Ready-made game elements include instant traps, pregenerated locations, and treasures.

Stronghold Builder's Guidebook: Although not designed for the revised edition of the game, the Stronghold
Builder's Guidebook offers tons of great inspiration for dungeon design, from magical locations to magic
augmentations on walls and floors that would send shivers down any adventurer's spine.

Lords of Darkness: Lords of Darkness presents many different factions, large and small, that could be
antagonists in the PCs adventures in Undermountain. Whether you want the PCs to meet slavers or assassins, a
thieves' guild or a cabal of necromancers, Lords of Darkness offers many tantalizing options.

Using Undermountain with Other Campaign Settings

You can use the rooms described in these articles in dungeons of your own devising, but you can also adapt all
of Undermountain for use in your campaign, whether or not you run a game in the Forgotten Realms.
 An Introduction

Eberron: Undermountain could be part of the depths of Sharn, or it could be a complex on the continent of
Xen'drik. In Sharn, the wide scope of the dungeon means that it would have to be part of the deepest foundations
of the city. In Xen'drik, you could raise the ceilings in Undermountain to 20 or 30 feet high and make the halls the
work of giants and later expansions by drow. Sharn: City of Towers is an excellent resource for using
Undermountain with Sharn.

Greyhawk: Countless locations exist that could host the halls of Undermountain. Perhaps the Undermountain
map represents a lost level of the dungeons of Castle Greyhawk, or maybe Maure Castle has depths beneath
the known levels.

About the Author

Once editor-in-chief of Dragon Magazine and now a game designer at Wizards of the Coast, Matthew Sernett
wrote in a Dragon editorial that there's nothing in D&D he likes better than when the adventurers flee through the
dungeon, running pell-mell through traps and past monsters because what chases them is worse. When he
wrote that, Matthew was thinking about Undermountain.

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