Undercity Sewers
By Skip and Penny Williams

Undercity Sewers contains encounters of level 2-10
and is suitable for use with any D&D campaign.

Local tales speak of many strange and dangerous things lurking below the gratings and drainpipes that lead to the sewers below the city streets. How many of these lurid stories are true? Or perhaps the tales don't go quite far enough.

Background for the DM

Generations ago, a fire swept through a city, prompting the city elders to undertake a massive reconstruction. They laid out new streets and created a network of aqueducts and wastewater tunnels beneath them. These new excavations lay alongside older catacombs and sub-basements. Over the years, property owners have built connections between many of the chambers and tunnels, creating a veritable labyrinth under the city.

The system still serves to carry clean water into the city and drain waste out, but a complex of freight tunnels also serves legitimate businesses, plus a larger network of delvings keeps certain less savory activities out of sight.

About Hertig and Rutjur

Thanks to his mongrelfolk heritage, Hertig has a bizarre appearance, with jug ears, protruding teeth, sparse hair, and clawlike hands and feet. Most mongrelfolk are timid if not downright cowardly. Hertig, however, showed a stalwart character from an early age by standing up to bullies of all sorts and generally protecting the weak. He also showed a talent for healing. But his tribal leaders considered Hertig's chivalrous heart a threat to the group. They wanted no heroes.

Hertig turned to an adventuring life but had trouble joining an effective group. Eventually, a cleric of Heironeous (or some other appropriate deity from your campaign) recognized Hertig's potential and arranged to have him educated. Hertig proved an apt pupil and quickly became a paladin (a vocation that fits his soul even if it belies his appearance). Hertig's superiors were at a loss when deciding what to do with him. He had winning ways, but he was hardly suitable for any public role in the religious hierarchy -- at least not in human lands. Ultimately, Hertig was assigned to guard the city sewers. His immunity to disease (courtesy of his paladin training) and dedication to serving the greater good made him ideal for the job.

Hertig's job requires him to monitor the sewers for intruders or damage and relay his findings to the surface authorities. He's also charged with protecting repair workers, rescuing anyone unfortunate (or foolish) enough to become lost in the sewers, and monitoring any illegal activities there. The recent defection of his assistant, Rutjur, to the Thieves' Guild (see below) undermines Hertig's efforts toward the latter task.

Though most humans fail to recognize them, Hertig has many gifts, including unflagging cheerfulness, courage, and an inexplicable talent for making friends and putting people at ease.

Statistics for Hertig at two different levels are given below.

Hertig: Male mongrelfolk paladin 3; CR 3; Medium humanoid (mongrelfolk); HD 3d10+6; hp 27; Init +0; Spd 30 ft.; AC 15, touch 10, flat-footed 15; Base Atk +3; Grapple +4; Atk and Full Atk +5 melee (1d8+1, masterwork morningstar) or +3 ranged (1d4+1, dart); SA smite evil 1/day; SQ aura of courage, aura of good, detect evil, diffuse blood, divine grace, divine health, emulate race, immunity to sleep effects, lay on hands, low-light vision, saving throw bonus (+1 against poison, enchantment spells or effects, and illusion spells or effects), sound imitation; AL LG; SV Fort +6, Ref +4, Will +3; Str 12, Dex 11, Con 14, Int 11, Wis 12, Cha 13.

Skills and Feats: Appraise +1, Climb +2, Diplomacy +4, Heal +4, Hide +4, Jump +2, Knowledge (dungeoneering) +2, Listen +4, Move Silently +1, Search +1, Sleight of Hand+5, Spot +4; Alertness, Lightning Reflexes.

Languages: Common.

Smite Evil (Su): Once per day, Hertig may attempt to smite evil with one normal melee attack. He adds +1 on his attack roll and deals an extra 3 points of damage.

Aura of Courage (Su): Immune to fear and each ally within 10 feet of him gains a +4 morale bonus on saving throws against fear effects.

Detect Evil (Sp):Detect evil at will as the spell.

Diffuse Blood: Mongrelfolk gain a +2 racial bonus on saving throws against any spell that targets a particular race or ignores a particular race, provided the selected race is part of their general ancestry (human).

Divine Health (Ex): Immunity to disease.

Emulate Race (Ex): Because of their radically mixed heritage, mongrelfolk can use magic items that function only for a user of a certain race. This ability works like the emulate race function of the Use Magic Device skill. A mongrelfolk can automatically emulate any humanoid race, with no need for a skill check. Mongrelfolk who have the Use Magic Device skill have a +4 racial bonus on attempts to emulate nonhumanoid races using that skill.

Sound Imitation (Ex): A mongrelfolk can mimic any voice or sound she has heard. Listeners must succeed on a DC 16 Will save to detect the ruse.

Possessions: +1 studded leather, masterwork light wooden shield, masterwork morningstar, 6 darts, 2 oil ofmagic weapon, potion ofcure moderate wounds,potion ofeagle's splendor,potion ofhide from animals,potion ofshield of faith, 10 sp.

Hertig: Male mongrelfolk paladin 5; CR 5; Medium humanoid (mongrelfolk); HD 5d10+10; hp 42; Init +0; Spd 30 ft.; AC 16, touch 11, flat-footed 16; Base Atk +5; Grapple +6; Atk and Full Atk +7 melee (1d8+1, masterwork morningstar) or +5 ranged (1d4+1, dart); SA smite evil 2/day, turn undead 5/day; SQ aura of courage, aura of good, detect evil, diffuse blood, divine grace, divine health, emulate race, immunity to sleep effects, lay on hands, low-light vision, saving throw bonus (+1 against poison, enchantment spells or effects, and illusion spells or effects), sound imitation, special mount (heavy warhorse, empathic link with mount, share spells with mount); AL LG; SV Fort +8, Ref +5, Will +4; Str 12, Dex 11, Con 14, Int 11, Wis 12, Cha 14.

Skills and Feats: Appraise +1, Climb +2, Concentration +4, Diplomacy +4, Heal +4, Hide +4, Jump +2, Knowledge (dungeoneering) +3, Listen +4, Move Silently +1, Search +1, Sleight of Hand+5, Spot +4; Alertness, Lightning Reflexes.

Languages: Common.

Smite Evil (Su): Twice per day, Hertig may attempt to smite evil with one normal melee attack. He adds +2 on his attack roll and deals an extra 5 points of damage.

Aura of Courage (Su): Immune to fear and each ally within 10 feet of him gains a +4 morale bonus on saving throws against fear effects.

Detect Evil (Sp):Detect evil at will as the spell.

Diffuse Blood: Mongrelfolk gain a +2 racial bonus on saving throws against any spell that targets a particular race or ignores a particular race, provided the selected race is part of their general ancestry (human).

Divine Health (Ex): Immunity to disease.

Emulate Race (Ex): Because of their radically mixed heritage, mongrelfolk can use magic items that function only for a user of a certain race. This ability works like the emulate race function of the Use Magic Device skill. A mongrelfolk can automatically emulate any humanoid race, with no need for a skill check. Mongrelfolk who have the Use Magic Device skill have a +4 racial bonus on attempts to emulate nonhumanoid races using that skill.

Sound Imitation (Ex): A mongrelfolk can mimic any voice or sound she has heard. Listeners must succeed on a DC 16 Will save to detect the ruse.

Special Mount (Sp): Once per day for up to 10 hours, Hertig can call upon his heavy warhorse as a full-round action. The creature's abilities and characteristics are summarized below.

Dragonfly: Heavy warhorse special mount; CR N/A; Large magical beast; HD 6d8+18; hp 45; Init +1; Spd 50 ft.; AC 18, touch 10, flat-footed 17; Base Atk +4; Grapple +12; Atk +9 melee (1d6+4, hoof); Full Atk +9 melee (1d6+4, 2 hooves) and +3 melee (1d4+2, bite); SQ empathic link, improved evasion, low-light vision, scent, share spells, share saving throws; AL LG; SV Fort +8, Ref +6, Will +3; Str 19, Dex 13, Con 17, Int 6, Wis 13, Cha 6.

Skills and Feats: Listen +6, Spot +5; Endurance, Run, Weapon Focus (hoof).

Special Mount Benefits (Ex): Hertig and Dragonfly enjoy the empathic link and share spells special qualities.

Empathic Link (Ex): Hertig can communicate telepathically with Dragonfly at a distance of up to 1 mile. The master has the same connection to an item or a place that the mount does.

Share Spells (Ex): Hertig may have any spell (but not any spell-like ability) he casts on himself also affect Dragonfly if the latter is within 5 feet at the time. Hertig may also cast a spell with a target of "You" on Dragonfly (as a touch range spell) of on himself. Hertig and Dragonfly may share spells even if the spells normally do not affect creatures of Dragonfly's type.

Possessions: +1 studded leather, masterwork light wooden shield, ring of protection +1, masterwork morningstar, 6 darts, 2 oil of magic weapon, potion of cure moderate wounds, potion of eagle's splendor, potion of hide from animals, potion of shield of faith, 10 sp.

Rutjur is a young human, about 19 years old, with a slender build, quick hands, and an insatiable curiosity. Rutjur is a foundling, abandoned at a temple of Hertig's faith as an infant. He showed a knack for getting along with animals at an early age, and he soon boasted that he would become a famous defender of the faith someday. Rutjur, however, has little patience for doing anything that doesn't come easily and thus far he has proven a failure as an apprentice cleric or paladin. In fact, he lacks the strength of will for either job. When Rutjur learned of Hertig and his job as guardian of the sewers, he practically begged to become Hertig's assistant; Rutjur was convinced life under the city would be one long adventure.

Life in the sewers turned out to be smelly, uncomfortable, and boring for Rutjur. The young man, however, has befriended several of the thieves who have hideouts in the sewers. He keeps his friends informed of Hertig's plans and whereabouts and the thieves have reciprocated by teaching Rutjur some of the finer points of living dishonestly. Eventually, Hertig will probably figure out how the criminals in the sewers outwit him, but until then Rutjur enjoys the double life he has found for himself. Rutjur doesn't see his actions as any kind of betrayal of Hertig's trust, just as something that keeps him entertained.

Rutjur: Male human expert 1/rogue 1; CR 2; Medium humanoid (human); HD 1d6+1 plus 1d6+1; hp 9; Init +2; Spd 30 ft.; AC 14, touch 12, flat-footed 12; Base Atk +0; Grapple +1; Atk and Full Atk +2 melee (1d6+1/19-20, masterwork short sword) or +3 ranged (1d8/19-20, masterwork light crossbow); SA sneak attack (+1d6); SQ trapfinding; AL CN; SV Fort +1, Ref +4, Will +2; Str 12, Dex 15, Con 13, Int 14, Wis 10, Cha 8.

Skills and Feats: Balance +6, Bluff +3, Disable Device +6, Handle Animal +1, Hide +6, Listen +7, Move Silently +6, Open Lock +6, Perform (wind instruments) +1, Spot +3, Swim +4, Tumble +5, Use Magic Device +1; Alertness, Lightning Reflexes.

Languages: Common.

Sneak Attack (Ex): Rutjur deals +1d6 extra points of damage on any successful attack against flat-footed or flanked targets, or against a target that has been denied its Dexterity bonus for any reason. This damage also applies to ranged attacks against targets up to 30 feet away. Creatures with concealment, creatures without discernible anatomies, and creatures immune to extra damage from critical hits are all immune to sneak attacks. Rutjur may choose to deliver nonlethal damage with his sneak attack, but only when using a weapon designed for that purpose, such as a sap (blackjack).

Trapfinding (Ex): Rutjur can find, disarm, or bypass traps with a DC of 20 or higher. He can use the Search skill to find, and the Disable Device skill to disarm, magic traps (DC 25 + the level of the spell used to create it). If his Disable Device result exceeds the trap's DC by 10 or more, he discovers how to bypass the trap without triggering or disarming it.

Possessions: Leather armor, masterwork short sword, dagger, masterwork light crossbow, 10 bolts, everburning torch,pipes of the sewers, thieves' tools, 20 sp.

The Setup

The sewer system described here can exist under any large town or small city, or it might simply be part of a much larger complex under a bigger community. For example, it might lie under a business district in a large city or metropolis.

The sewers are far from deserted. The city elders were all too aware that the sewers could serve as a refuge for outlaws or a route into the city for invaders, so they took care to stock the tunnels with a few guardians. Today, these guardians often come into conflict with the sewers' clandestine elements and create an ongoing struggle that the surface dwellers know very little about. Player characters who own buildings or who are affiliated with a thieves' guild or similar organization might already be familiar with sewers and their denizens. Others characters might require an introduction, such as one of the following:

• The PCs witness a thunderstorm in which balls of lightning literally shoot up out of the sewers and dance along the street, only to disappear into the sewers again.
  
  The balls of lightning might be natural electrical discharges or flaming bits of sewer gas. If the PCs choose to pursue or investigate them, treat them as flaming sphere effects. They move randomly up to 30 feet each round. Use the splash weapon miss diagram on page 158 in the Player's Handbook to determine the direction they move each round, but assume they move directly toward any sewer entrance within 30 feet (except on the round after they emerge). A ball deals 2d6 points of fire or electricity damage, or 1d6 points of each, or perhaps no damage at all, to anything it strikes.
  
  The balls also might be will-o-wisps from one of the settling basins (see below).
  
  
• The PCs hear tales of shadow figures staring out from behind sewer gratings (or perhaps a PC with a fairly high Spot bonus sees such a figure).
  
  The figures might be rogues from the local thieves' guild watching the street, or they might be Hertig or his assistant, Rutjur, taking a peek outside (see below).
  
  
• The PCs hear tales of a deformed creature that lurks in the sewers. Some say this creature is benign, but others insist that it is a hideous fiend or insane wizard who is breeding an army to take over the city and devour its citizens.
  
  The tales refer to Hertig, the little-known guardian of the sewers. The more macabre stories are distortions.
  
  
• The PCs are hired to enter the sewers and track down a lost or stolen item.
  
  The item's owner might have simply dropped the item in question, or perhaps a pickpocket or burglar has stolen it. For a twist on this theme, perhaps Hertig already has found and returned the item and the owner wants to deliver a reward.

Exploring the Sewers

The sewers contain many different kinds of tunnels and chambers. Here's a sampling of what visitors might find.

Entrances

Characters can access the sewers several different ways.

Gratings: The city's major streets are equipped with gutters and gratings that drain off rainwater. Residents also push nightsoil and other trash into these gratings. Most gratings are permanently fixed into place, and they don't offer egress for many creatures bigger than size Diminutive. Others are equipped with hinges and padlocks that allow the grate to open for cleaning. Still others have been surreptitiously converted into secret doors (usually by the sewers' less savory denizens). All these gratings have the same basic statistics, as noted below.

Each grating leads to a vertical shaft that is 10 to 25 feet long and lined with smooth masonry (Climb DC 20). If the grating is designed to be opened, iron rungs are set into the shaft (Climb DC 5).

Grating: 4 in. thick; hardness 10; hp 120; break DC 27, Open Lock DC 25 (if padlocked), Search DC 25 (to locate opening mechanism when the grating is a secret door).

Drainage Tunnels (EL 2-7)

These structures carry storm runoff and other wastes away from the city. The entire network leads to a single outlet set in some inaccessible place (a cliff face, marsh, or river bottom), where the effluent is discharged. A typical drainage tunnel is about 7 feet high and 10 to 20 feet wide. A tunnel floor has walkways about 2-1/2 feet wide along both walls and a trough 10 feet deep in between. The walkways usually prove damp and slightly slippery. Any Large or bigger creature must make a DC 12 Balance check to move along the walkways at half speed. A Small or Medium creature can move at full speed but must make a DC 7 Balance check to fight, charge, or run on the walkways. Tiny and smaller creatures can use the walkways without making Balance checks.

Creatures: PCs may meet roving denizens of the sewers while moving along the walkways.

Bat Swarm: hp 13; see Monster Manual page 237.

These creatures roost in the sewers during the day and crawl to the surface at night, where they fly around hunting insects. If disturbed, the bats flee. Some locations might include rookeries. In such places, the bats defend their young.

Rat Swarms (1-3): hp 13 each; see Monster Manual page 239.

The rats attack any living creatures they encounter.

Ochre Jelly: hp 69; see Monster Manual page 202.

These creatures usually cling to the walls. They live by scooping detritus from the troughs, but will attack other creatures when they get the chance. When at rest, they look like patches of lichen on the walls.

Black Pudding: hp 115; see Monster Manual page 201.

These creatures act just like the ochre jellies, except that they resemble sooty or oily patches on the walls.

Sewer Workers: See the Main Settling Basin entry.

The PCs might meet Hertig or his assistant, Rutjur, out making their rounds. See Main Settling Basin entry for details.

Thugs: See the Sub-Basements entry.

These groups of fighters, rogues, and clerics are generally hostile; see the Sub-Basements entry for details.

Other Creatures: The residents in a nearby settling basin might be out hunting; see the Settling Basin entry.

Settling Basins (EL 2-7)

Large, brick-lined ponds are located throughout the sewers. Wastewater collects in the basins and any sediment in it settles out. Storms cause water to surge into the basins, forcing the clearer water near the surface out.

Most settling basins are circular and about 30 feet wide, with a 5-foot walkway all around. From two to six drainage tunnels feed into each basin. Half the tunnels are sloped to drain out of the basin and the remainder drain in.

Creatures: Many settling basins teem with creatures. The city elders stocked the basins with some of these creatures to provide the city with some security. Other creatures have simply moved in and settled down.

Crocodiles (1-3): hp 22 each; see Monster Manual page 271.

These creatures usually float near the walkways, waiting to ambush anything that comes too close.

Shocker Lizards (3-5): hp 13 each; see Monster Manual page 224.

The lizards usually spread out in the chamber, with some in the water and some clinging to the walls, but always within 20 feet of each other. The lizards are fairly nervous, but not overly aggressive. One lizard usually hisses a warning before the whole group looses a lethal shock.

Juvenile Tojanida (1-2): hp 19 each; see Monster Manual page 244.

These creatures usually aren't aggressive toward other intelligent creatures. They're willing to share whatever information they have about the sewers or the city above in exchange for a few morsels of food. The tojanidas know Hertig and Rutjur and they like the pair (see the Main Settling Basin entry). They've also met many other intelligent residents of the sewers, and they're less fond of them (see the Sub-Basements entry).

Otyugh: hp 36; see Monster Manual page 204.

An otyugh usually finds a mound of sediment and stands on it. Most of the time, it stays submerged and uses its eyestalk like a periscope. It kicks its way to the surface now and then for a breath. The creature generally tries to wait until a group exits the chamber, then attacks the last person to leave.

Adult Tojanida: hp 45; see Monster Manual page 243.

These creatures usually act much like their juvenilebrethren, but tend to be more lucid.

Sub-Basements (EL 5-10)

These chambers usually are located under abandoned buildings. Some, however, lie under newer buildings whose occupants are unaware (or claim to be unaware) of their existence. Some sub-basements are single chambers (perhaps 20 to 40 feet square); others are complexes of several chambers. A few sub-basements have plain, stone doors that open onto a drainage tunnel or settling basin. Most of them, however, have secret doors. Most sub-basements are built above the level of the surrounding sewers, and short flights of steps lead up from the doors into the basement.

Stone Doors or Stone Secret Doors: 4 in. thick; hardness 8; hp 60; break DC 23 (28 if locked), Open Lock DC 25, Search DC 25 (for secret doors).

Creatures: Sub-basements are havens for thieves, smugglers, evil clerics, and one black dragon. Most of the people change their lodgings from time to time, moving from one sub-basement to another. An occupied sub-basement often contains one or two thieves or clerics of levels 2-4 with one or two fighters of levels 1-3 for each thief or cleric. Use the NPC statistics in Chapter 4 of the Dungeon Master's Guide.

These characters live unsavory lives and tend to attack visitors unless bribed or expertly persuaded to be peaceful. Most of these characters despise Hertig as a meddling do-gooder. They're reluctant to kill him, however, because they fear retribution from the city government. A few of the thieves have befriended Rutjur, Hertig's restless assistant. They have taught the youngster an array of thieving skills and have gained his trust. They use that trust to get information about Hertig's plans and movements.

Young Adult Black Dragon: hp 157; see Monster Manual page 72.

The dragon, Ehilunthurix, is a fairly new arrival to the sewers. Hertig suspects the dragon's presence, but has not located its lair, nor does he know how big it is. Ehilunthurix thinks herself invincible and gladly spares the PCs' lives in exchange for a magic item or a few hundred gold pieces worth of gems. Ironically, Ehilunthurix is helping Hertig with his job. The dragon has been harassing the criminal element in the sewers in an attempt to take control.

Ehilunthurix makes her lair in a partially flooded complex of three chambers.

Main Settling Basin (EL 4-5)

As noted earlier, the network of settling basins and drainage tunnels in the sewers leads to a big settling basin 70 feet in diameter surrounded by a walkway 10 feet wide.

Creatures: Hertig and Rutjur dwell here in a series of sub-basements that adjoin the main chamber (see the About Hertig and Rutjur section for statistics). Each has a fairly snug and dry bedchamber with a narrow bed, table, chair, and chest for spare clothes and sundry items. At least one of the pair is home at any given time.

Tactics: Hertig would rather negotiate than fight. If he has advance warning of an encounter, Hertig prefers to hide and observe the newcomers for awhile. If the strangers don't seem dangerous, he plays the role of a beggar or confused workman, all the while attempting to get the strangers to reveal who they are and what they want.

If the PCs ask Hertig about his business, he claims to be a workman assigned to fix broken tiles in the walkways.

If the PCs claim they have come in search of treasure, Hertig laughs and tells them that he has found plenty of treasure here. He then extracts a broken piece of glass and shows it to them. "Lots more like this down here," he says. If the PCs tell him they are in search of a particular sewer-dwelling creature, he warns them of the dangers of the creatures below. "Beware the dragon!" he says. If the PCs have already seen the crocodiles, they may laugh off this warning.

If the characters tell Hertig they have come in search of a thieves' conclave, he insists that such things are not for nice people and tells them to leave. Rutjur, however, may try to signal a PC in the rear of the party to follow him to the nearest thieves' den.

If the PCs go off to slay sewer monsters, Hertig follows along behind to make sure they aren't in over their heads. Should the battle prove too difficult for them, he joins in the fight.

Should a fight break out with the PCs, Hertig tries to defeat the enemy leader with his morningstar. He'll call Dragonfly (if available) and have the warhorse attack the enemy flank (Hertig is no rider). If necessary, Hertig will withdraw from battle just long enough to get out of sight so that he can hide again. He then waits to renew the attack for a more opportune time.

Rutjur is headstrong and spoiling for a fight, but he's not quite brave enough to meet a foe head-on. Like Hertig, Rutjur prefers to hide when trouble approaches. Unlike Hertig, Rutjur also likes to sneak attack unsuspecting foes.

When the two face trouble together, Rutjur usually stays in hiding while Hertig speaks. If violence erupts, Rutjur sneak attacks the nearest foe, then tries to team up with Hertig to flank someone.

Treasure: Hertig keeps various trinkets and oddments that he has gleaned from the sewers heaped in a chamber near his own. Bits of cracked pottery, tattered clothing, broken toys, and bent tableware cram the dank cell. Hertig claims that everything he owns that is worth anything lies in the chamber. In fact, the collection includes one gem -- a piece of garnet worth 10 gp. Hertig knows just where the gem is, but an intruder would have to make an effort to find it (DC 25 Search check).

About the Authors

Skip Williams keeps busy with freelance projects for several different game companies and was the Sage of Dragon Magazine for 18 years. Skip is a co-designer of the D&D 3rd Edition game and the chief architect of the Monster Manual. When not devising swift and cruel deaths for player characters, Skip putters in his kitchen or garden (rabbits and deer are not Skip's friends) or works on repairing and improving the century-old farmhouse that he shares with his wife, Penny, and a growing menagerie of pets.

Penny Williams joined the roleplaying game industry as Game Questions Expert for TSR, Inc. in the 1980s. Since then, she has served as RPGA Network Coordinator, PolyhedronNewszine editor, and Senior Editor and Coordinating Editor for the RPG R&D Department at Wizards of the Coast, Inc. Now a busy freelancer, Penny edits for several game companies and runs the online playtesting program for Wizards products. When not enhancing the cruelty of the deaths PCs will suffer at the hands of designers, Penny puts up jam, works jigsaw puzzles, and tutors students in math and science.