Dungeons & Traps

Dungeons & Traps

This page covers dungeon design and mapping conventions, and the rules for traps: how they work, how characters detect and disable them, and a set of sample traps ready to drop into an adventure. See Wilderness & Urban Adventures for outdoor and city environments, and Weather, Planes & Environmental Rules for climate and hazard rules.

Dungeons

Of all the strange places that an adventurer might explore, none is deadlier than the dungeon. These labyrinths, full of deadly traps, hungry monsters, and priceless treasure, test every skill a character possesses. These rules can apply to dungeons of any type, from the wreck of a sunken ship to a vast cave complex.

Types of Dungeons

The four basic dungeon types are defined by their current status. Many dungeons are variations on these basic types or combinations of more than one of them. Sometimes old dungeons are used again and again by different inhabitants for different purposes.

Ruined Structure

Once occupied, this place is now abandoned (completely or in part) by its original creator or creators, and other creatures have wandered in. Many subterranean creatures look for abandoned underground constructions in which to make their lairs. Any traps that might exist have probably been set off, but wandering beasts might very well be common.

Occupied Structure

This type of dungeon is still in use. Creatures (usually intelligent) live there, although they might not be the dungeon’s creators. An occupied structure might be a home, a fortress, a temple, an active mine, a prison, or a headquarters. This type of dungeon is less likely to have traps or wandering beasts, and more likely to have organized guards–both on watch and on patrol. Traps or wandering beasts that might be encountered are usually under the control of the occupants. Occupied structures have furnishings to suit the inhabitants, as well as decorations, supplies, and the ability for occupants to move around. The inhabitants might have a communication system, and they almost certainly control an exit to the outside.

Some dungeons are partially occupied and partially empty or in ruins. In such cases, the occupants are typically not the original builders, but instead a group of intelligent creatures that have set up their base, lair, or fortification within an abandoned dungeon.

Safe Storage

When people want to protect something, they sometimes bury it underground. Whether the item they want to protect is a fabulous treasure, a forbidden artifact, or the dead body of an important figure, these valuable objects are placed within a dungeon and surrounded by barriers, traps, and guardians.

The safe storage dungeon is the most likely to have traps but the least likely to have wandering beasts. This type of dungeon is normally built for function rather than appearance, but sometimes it has ornamentation in the form of statuary or painted walls. This is particularly true of the tombs of important people.

Sometimes, however, a vault or a crypt is constructed in such a way as to house living guardians. The problem with this strategy is that something must be done to keep the creatures alive between intrusion attempts. Magic is usually the best solution to provide food and water for these creatures. Builders of vaults or tombs often use undead creatures or constructs, both of which have no need for sustenance or rest, to guard their dungeons. Magic traps can attack intruders by summoning monsters into the dungeon that disappear when their task is done.

Natural Cavern Complex

Underground caves provide homes for all sorts of subterranean monsters. Created naturally and connected by labyrinthine tunnel systems, these caverns lack any sort of pattern, order, or decoration. With no intelligent force behind its construction, this type of dungeon is the least likely to have traps or even doors.

Fungi of all sorts thrive in caves, sometimes growing in huge forests of mushrooms and puffballs. Subterranean predators prowl these forests, looking for weaker creatures feeding upon the fungi. Some varieties of fungus give off a phosphorescent glow, providing a natural cavern complex with its own limited light source. In other areas, a daylight spell or similar magical effect can provide enough light for green plants to grow.

Natural cavern complexes often connect with other types of dungeons, the caves having been discovered when the manufactured dungeons were delved. A cavern complex can connect two otherwise unrelated dungeons, sometimes creating a strange mixed environment. A natural cavern complex joined with another dungeon often provides a route by which subterranean creatures find their way into a manufactured dungeon and populate it.

Dungeon Terrain

The following rules cover the basics of terrain that can be found in a dungeon.

Walls

Masonry walls–stones piled on top of each other, usually but not always held in place with mortar–often divide dungeons into corridors and chambers. Dungeon walls can also be hewn from solid rock, leaving them with a rough, chiseled look. Still other dungeon walls can be the smooth, unblemished stone of a naturally occurring cave. Dungeon walls are difficult to break down or through, but they’re generally easy to climb.

Table: Walls

Masonry Walls

The most common kind of dungeon wall, masonry walls are usually at least 1 foot thick. Often, these ancient walls sport cracks and crevices, and sometimes dangerous slimes or small monsters live in these areas and wait for prey. Masonry walls stop all but the loudest noises. It takes a DC 20 Climb check to travel along a masonry wall.

Superior Masonry Walls

Sometimes masonry walls are better built (smoother, with tighter-fitting stones and less cracking), and occasionally these superior walls are covered with plaster or stucco. Covered walls often bear paintings, carved reliefs, or other decoration. Superior masonry walls are no more difficult to destroy than regular masonry walls but are more difficult to climb (DC 25).

Reinforced Masonry Walls

These are masonry walls with iron bars on one or both sides of the wall, or placed within the wall to strengthen it. The hardness of a reinforced wall remains the same, but its hit points are doubled and the Strength check DC to break through it is increased by 10.

Hewn Stone Walls

Such walls usually result when a chamber or passage is tunneled out from solid rock. The rough surface of a hewn wall frequently provides minuscule ledges where fungus grows and fissures where vermin, bats, and subterranean snakes live. When such a wall has an “other side” (meaning it separates two chambers in the dungeon), the wall is usually at least 3 feet thick; anything thinner risks collapsing from the weight of all the stone overhead. It takes a DC 25 Climb check to climb a hewn stone wall.

Unworked Stone Walls

These surfaces are uneven and rarely flat. They are smooth to the touch but filled with tiny holes, hidden alcoves, and ledges at various heights. They’re also usually wet or at least damp, since it’s water that most frequently creates natural caves. When such a wall has an “other side,” the wall is usually at least 5 feet thick. It takes a DC 15 Climb check to move along an unworked stone wall.

Iron Walls

These walls are placed within dungeons around important places, such as vaults.

Paper Walls

Paper walls are placed as screens to block line of sight, but nothing more.

Wooden Walls

Wooden walls often exist as recent additions to older dungeons, used to create animal pens, storage bins, and temporary structures, or just to make a number of smaller rooms out of a larger one.

Magically Treated Walls

These walls are stronger than average, with a greater hardness, more hit points, and a higher break DC. Magic can usually double the hardness and hit points of a wall and add up to 20 to the break DC. A magically treated wall also gains a saving throw against spells that could affect it, with the save bonus equaling 2 + 1/2 the caster level of the magic reinforcing the wall. Creating a magic wall requires the Craft Wondrous Item feat and the expenditure of 1,500 gp for each 10-foot-by-10-foot wall section.

Walls with Arrow Slits

Walls with arrow slits can be made of any durable material but are most commonly masonry, hewn stone, or wood. Such a wall allows defenders to fire arrows or crossbow bolts at intruders from behind the safety of the wall. Archers behind arrow slits have improved cover that gives them a +8 bonus to Armor Class, a +4 bonus on Reflex saves, and the benefits of the improved evasion class feature.

Floors

As with walls, dungeon floors come in many types.

Flagstone

Like masonry walls, flagstone floors are made of fitted stones. They are usually cracked and only somewhat level. Slime and mold grows in the cracks. Sometimes water runs in rivulets between the stones or sits in stagnant puddles. Flagstone is the most common dungeon floor.

Uneven Flagstone

Over time, some floors can become so uneven that a DC 10 Acrobatics check is required to run or charge across the surface. Failure means the character can’t move that round. Floors as treacherous as this should be the exception, not the rule.

Hewn Stone Floors

Rough and uneven, hewn floors are usually covered with loose stones, gravel, dirt, or other debris. A DC 10 Acrobatics check is required to run or charge across such a floor. Failure means the character can still act, but can’t run or charge in this round.

Light Rubble

Small chunks of debris litter the ground. Light rubble adds 2 to the DC of Acrobatics checks.

Dense Rubble

The ground is covered with debris of all sizes. It costs 2 squares of movement to enter a square with dense rubble. Dense rubble adds 5 to the DC of Acrobatics checks, and it adds 2 to the DC of Stealth checks.

Smooth Stone Floors

Finished and sometimes even polished, smooth floors are found only in dungeons made by capable and careful builders.

Natural Stone Floors

The floor of a natural cave is as uneven as the walls. Caves rarely have flat surfaces of any great size. Rather, their floors have many levels. Some adjacent floor surfaces might vary in elevation by only a foot, so that moving from one to the other is no more difficult than negotiating a stair step, but in other places the floor might suddenly drop off or rise up several feet or more, requiring Climb checks to get from one surface to the other. Unless a path has been worn and well marked in the floor of a natural cave, it takes 2 squares of movement to enter a square with a natural stone floor, and the DC of Acrobatics checks increases by 5. Running and charging are impossible, except along paths.

Slippery

Water, ice, slime, or blood can make any of the dungeon floors described in this section more treacherous. Slippery floors increase the DC of Acrobatics checks by 5.

Grate

A grate often covers a pit or an area lower than the main floor. Grates are usually made from iron, but large ones can also be made from iron-bound timbers. Many grates have hinges to allow access to what lies below (such grates can be locked like any door), while others are permanent and designed to not move. A typical 1-inch-thick iron grate has 25 hit points, hardness 10, and a DC of 27 for Strength checks to break through it or tear it loose.

Ledge

Ledges allow creatures to walk above some lower area. They often circle around pits, run along underground streams, form balconies around large rooms, or provide a place for archers to stand while firing upon enemies below. Narrow ledges (12 inches wide or less) require those moving along them to make Acrobatics checks. Failure results in the moving character falling off the ledge. Ledges sometimes have railings along the wall. In such a case, characters gain a +5 circumstance bonus on Acrobatics checks to move along the ledge. A character who is next to a railing gains a +2 circumstance bonus on his opposed Strength check to avoid being bull rushed off the edge.

Ledges can also have low walls 2 to 3 feet high along their edges. Such walls provide cover against attackers within 30 feet on the other side of the wall, as long as the target is closer to the low wall than the attacker is.

Transparent Floor

Transparent floors, made of reinforced glass or magic materials (even a wall of force), allow a dangerous setting to be viewed safely from above. Transparent floors are sometimes placed over lava pools, arenas, monster dens, and torture chambers. They can be used by defenders to watch key areas for intruders.

Sliding Floors

A sliding floor is a type of trap door, designed to be moved and thus reveal something that lies beneath it. A typical sliding floor moves so slowly that anyone standing on one can avoid falling into the gap it creates, assuming there’s somewhere else to go. If such a floor slides quickly enough that there’s a chance of a character falling into whatever lies beneath–a spiked pit, a vat of burning oil, or a pool filled with sharks–then it’s a trap.

Trap Floors

Some floors are designed to become suddenly dangerous. With the application of just the right amount of weight, or the pull of a lever somewhere nearby, spikes protrude from the floor, gouts of steam or flame shoot up from hidden holes, or the entire floor tilts. These strange floors are sometimes found in arenas, designed to make combats more exciting and deadly. Construct these floors as you would any other trap.

Doors

Doors in dungeons are much more than mere entrances and exits. Often they can be encounters all by themselves. Dungeon doors come in three basic types: wooden, stone, and iron.

Table: Doors

• DC to lift. Use appropriate door figure for breaking.

Wooden Doors

Constructed of thick planks nailed together, sometimes bound with iron for strength (and to reduce swelling from dungeon dampness), wooden doors are the most common type. Wooden doors come in varying strengths: simple, good, and strong. Simple doors (break DC 15) are not meant to keep out motivated attackers. Good doors (break DC 18), while sturdy and long-lasting, are still not meant to take much punishment. Strong doors (break DC 25) are bound in iron and are a sturdy barrier to those attempting to get past them. Iron hinges fasten the door to its frame, and typically a circular pull-ring in the center is there to help open it. Sometimes, instead of a pull-ring, a door has an iron pull-bar on one or both sides of the door to serve as a handle. In inhabited dungeons, these doors are usually well-maintained (not stuck) and unlocked, although important areas are locked up if possible.

Stone

Carved from solid blocks of stone, these heavy, unwieldy doors are often built so that they pivot when opened, although dwarves and other skilled craftsfolk are able to fashion hinges strong enough to hold up a stone door. Secret doors concealed within a stone wall are usually stone doors. Otherwise, such doors stand as tough barriers protecting something important beyond. Thus, they are often locked or barred.

Iron

Rusted but sturdy, iron doors in a dungeon are hinged like wooden doors. These doors are the toughest form of nonmagical door. They are usually locked or barred.

Breaking Doors

Dungeon doors might be locked, trapped, reinforced, barred, magically sealed, or sometimes just stuck. All but the weakest characters can eventually knock down a door with a heavy tool such as a sledgehammer, and a number of spells and magic items give characters an easy way around a locked door.

Attempts to literally chop down a door with a slashing or bludgeoning weapon use the hardness and hit points given in Table: Doors. When assigning a DC to an attempt to knock a door down, use the following as guidelines.

DC 10 or Lower

a door just about anyone can break open.

DC 11-15

a door that a strong person could break with one try and an average person might be able to break with one try.

DC 16-20

a door that almost anyone could break, given time.

DC 21-25

a door that only a strong or very strong person has a hope of breaking, probably not on the first try.

DC 26 or Higher

a door that only an exceptionally strong person has a hope of breaking.

Locks

Dungeon doors are often locked, and thus the Disable Device skill comes in very handy. Locks are usually built into the door, either on the edge opposite the hinges or right in the middle of the door. Built-in locks either control an iron bar that juts out of the door and into the wall of its frame, or else a sliding iron bar or heavy wooden bar that rests behind the entire door. By contrast, padlocks are not built-in but usually run through two rings, one on the door and the other on the wall. More complex locks, such as combination locks and puzzle locks, are usually built into the door itself. Because such keyless locks are larger and more complex, they are typically only found in sturdy doors (strong wooden, stone, or iron doors).

The Disable Device DC to pick a lock often falls within the range of 20 to 30, although locks with lower or higher DCs can exist. A door can have more than one lock, each of which must be unlocked separately. Locks are often trapped, usually with poison needles that extend out to prick a rogue’s finger.

Breaking a lock is sometimes quicker than breaking the whole door. If a PC wants to whack at a lock with a weapon, treat the typical lock as having hardness 15 and 30 hit points. A lock can only be broken if it can be attacked separately from the door, which means that a built-in lock is immune to this sort of treatment. In an occupied dungeon, every locked door should have a key somewhere.

A special door might have a lock with no key, instead requiring that the right combination of nearby levers must be manipulated or the right symbols must be pressed on a keypad in the correct sequence to open the door.

Stuck Doors

Dungeons are often damp, and sometimes doors get stuck, particularly wooden doors. Assume that about 10% of wooden doors and 5% of non-wooden doors are stuck. These numbers can be doubled (to 20% and 10%, respectively) for long-abandoned or neglected dungeons.

Barred Doors

When characters try to bash down a barred door, it’s the quality of the bar that matters, not the material the door is made of. It takes a DC 25 Strength check to break through a door with a wooden bar, and a DC 30 Strength check if the bar is made of iron. Characters can attack the door and destroy it instead, leaving the bar hanging in the now-open doorway.

Magic Seals

Spells such as arcane lock can discourage passage through a door. A door with an arcane lock spell on it is considered locked even if it doesn’t have a physical lock. It takes a knock spell, a dispel magic spell, or a successful Strength check to open such a door.

Hinges

Most doors have hinges, but sliding doors do not. They usually have tracks or grooves instead, allowing them to slide easily to one side.

Standard Hinges

These hinges are metal, joining one edge of the door to the door frame or wall. Remember that the door swings open toward the side with the hinges. (So, if the hinges are on the PCs’ side, the door opens toward them; otherwise it opens away from them.) Adventurers can take the hinges apart one at a time with successful Disable Device checks (assuming the hinges are on their side of the door, of course). Such a task has a DC of 20 because most hinges are rusted or stuck. Breaking a hinge is difficult. Most have hardness 10 and 30 hit points. The break DC for a hinge is the same as for breaking down the door.

Nested Hinges

These hinges are much more complex than ordinary hinges, and are found only in areas of excellent construction. These hinges are built into the wall and allow the door to swing open in either direction. PCs can’t get at the hinges to fool with them unless they break through the door frame or wall. Nested hinges are typically found on stone doors but sometimes on wooden or iron doors as well.

Pivots

Pivots aren’t really hinges at all, but simple knobs jutting from the top and bottom of the door that fit into holes in the door frame, allowing the door to spin. The advantages of pivots are that they can’t be dismantled like hinges and they’re simple to make. The disadvantage is that since the door pivots on its center of gravity (typically in the middle), nothing larger than half the door’s width can fit through without squeezing. Doors with pivots are usually stone and often quite wide to overcome this disadvantage. Another solution is to place the pivot toward one side and have the door be thicker at that end and thinner toward the other end so that it opens more like a normal door. Secret doors in walls often turn on pivots, since the lack of hinges makes it easier to hide the door’s presence. Pivots also allow objects such as bookcases to be used as secret doors.

Secret Doors

Disguised as a bare patch of wall (or floor or ceiling), a bookcase, a fireplace, or a fountain, a secret door leads to a secret passage or room. Someone examining the area finds a secret door, if one exists, on a successful Perception check (DC 20 for a typical secret door to DC 30 for a well-hidden secret door).

Many secret doors require special methods of opening, such as hidden buttons or pressure plates. Secret doors can open like normal doors, or they might pivot, slide, sink, rise, or even lower like a drawbridge to permit access. Builders might put a secret door low near the floor or high in a wall, making it difficult to find or reach. Wizards and sorcerers have a spell, phase door , that allows them to create a magic secret door that only they can use.

Magic Doors

Enchanted by the original builders, a door might speak to explorers, warning them away. It might be protected from harm, increasing its hardness or giving it more hit points as well as an improved saving throw bonus against disintegrate and similar spells. A magic door might not lead into the space behind it, but instead might be a portal to a faraway place or even another plane of existence. Other magic doors might require passwords or special keys to open them.

Portcullises

These special doors consist of iron or thick, ironbound wooden shafts that descend from recesses in the ceilings above archways. Sometimes a portcullis has crossbars that create a grid, sometimes not. Typically raised by means of a winch or a capstan, a portcullis can be dropped quickly, and the shafts end in spikes to discourage anyone from standing underneath (or from attempting to dive under it as it drops). Once it is dropped, a portcullis locks, unless it is so large that no normal person could lift it anyway. In any event, lifting a typical portcullis requires a DC 25 Strength check.

Walls, Doors, and Detect Spells

Stone walls, iron walls, and iron doors are usually thick enough to block most detect spells, such as detect thoughts. Wooden walls, wooden doors, and stone doors are usually not thick enough to do so. A secret stone door built into a wall and as thick as the wall itself (at least 1 foot) does block most detect spells.

Stairs

Stairs are the most common means of traveling up and down within a dungeon. A character can move up or down stairs as part of their movement without penalty, but they cannot run on them. Increase the DC of any Acrobatics skill check made on stairs by 4. Some stairs are particularly steep and are treated as difficult terrain.

Cave-Ins and Collapses

Cave-ins and collapsing tunnels are extremely dangerous. Not only do dungeon explorers face the danger of being crushed by tons of falling rock, but even if they survive they might be buried beneath a pile of rubble or cut off from the only known exit. A cave-in buries anyone in the middle of the collapsing area, and then sliding debris damages anyone in the periphery of the collapse. A typical corridor subject to a cave-in might have a bury zone with a 15-foot radius and a 10-foot-wide slide zone extending beyond the bury zone. A weakened ceiling can be spotted with a DC 20 Knowledge (engineering) or DC 20 Craft (stonemasonry) check. Remember that Craft checks can be made untrained as Intelligence checks. A dwarf can make such a check if he simply passes within 10 feet of a weakened ceiling.

A weakened ceiling might collapse when subjected to a major impact or concussion. A character can cause a cave-in by destroying half the pillars holding up the ceiling.

Characters in the bury zone of a cave-in take 8d6 points of damage, or half that amount if they make a DC 15 Reflex save. They are subsequently buried. Characters in the slide zone take 3d6 points of damage, or no damage at all if they make a DC 15 Reflex save. Characters in the slide zone who fail their saves are buried.

Characters take 1d6 points of nonlethal damage per minute while buried. If such a character falls unconscious, he must make a DC 15 Constitution check each minute. If it fails, he takes 1d6 points of lethal damage each minute until freed or dead.

Characters who aren’t buried can dig out their friends. In 1 minute, using only her hands, a character can clear rocks and debris equal to five times her heavy load limit. The amount of loose stone that fills a 5-foot-by-5-foot area weighs 1 ton (2,000 pounds). Armed with an appropriate tool, such as a pick, crowbar, or shovel, a digger can clear loose stone twice as quickly as by hand. A buried character can attempt to free himself with a DC 25 Strength check.

Slimes, Molds, and Fungi

In a dungeon’s damp, dark recesses, molds and fungi thrive. For purposes of spells and other special effects, all slimes, molds, and fungi are treated as plants. Like traps, dangerous slimes and molds have CRs, and characters earn XP for encountering them.

A form of glistening organic sludge coats almost anything that remains in the damp and dark for too long. This kind of slime, though it might be repulsive, is not dangerous. Molds and fungi flourish in dark, cool, damp places. While some are as inoffensive as the normal dungeon slime, others are quite dangerous. Mushrooms, puffballs, yeasts, mildew, and other sorts of bulbous, fibrous, or flat patches of fungi can be found throughout most dungeons. They are usually inoffensive, and some are even edible (although most are unappealing or odd-tasting).

Brown Mold

Brown mold feeds on warmth, drawing heat from anything around it. It normally comes in patches 5 feet in diameter, and the temperature is always cold in a 30-foot radius around it. Living creatures within 5 feet of it take 3d6 points of nonlethal cold damage. Fire brought within 5 feet of brown mold causes the mold to instantly double in size. Cold damage, such as from a cone of cold , instantly destroys it.

Green Slime

This dungeon peril is a dangerous variety of normal slime. Green slime devours flesh and organic materials on contact and is even capable of dissolving metal. Bright green, wet, and sticky, it clings to walls, floors, and ceilings in patches, reproducing as it consumes organic matter. It drops from walls and ceilings when it detects movement (and possible food) below.

A single 5-foot square of green slime deals 1d6 points of Constitution damage per round while it devours flesh. On the first round of contact, the slime can be scraped off a creature (destroying the scraping device), but after that it must be frozen, burned, or cut away (dealing damage to the victim as well). Anything that deals cold or fire damage, sunlight, or a remove disease spell destroys a patch of green slime. Against wood or metal, green slime deals 2d6 points of damage per round, ignoring metal’s hardness but not that of wood. It does not harm stone.

Phosphorescent Fungus

This strange underground fungus gives off a soft violet glow that illuminates underground caverns and passages as well as a candle does. Rare patches of fungus illuminate as well as a torch does.

Shrieker

This human-sized purple mushroom emits a piercing sound that lasts for 1d3 rounds whenever there is movement or a light source within 10 feet. This shriek makes it impossible to hear any other sound within 50 feet. The sound attracts nearby creatures that are disposed to investigate it. Some creatures that live near shriekers learn that this noise means there is food or an intruder nearby.

Yellow Mold

If disturbed, a 5-foot square of this mold bursts forth with a cloud of poisonous spores. All within 10 feet of the mold must make a DC 15 Fortitude save or take 1d3 points of Constitution damage. Another DC 15 Fortitude save is required once per round for the next 5 rounds, to avoid taking 1d3 points of Constitution damage each round. A successful Fortitude save ends this effect. Fire destroys yellow mold, and sunlight renders it dormant.

Traps

Traps are a common danger in dungeon environments. From gouts of white-hot flame to hails of poisoned darts, traps can serve to protect valuable treasure or stop intruders from proceeding.

Elements of a Trap

All traps–mechanical or magical–have the following elements: CR, type, Perception DC, Disable Device DC, trigger, reset, and effect. Some traps might also include optional elements, such as poison or a bypass. These characteristics are described below.

Type

A trap can be either mechanical or magical in nature.

Mechanical

Dungeons are frequently equipped with deadly mechanical (nonmagical) traps. A trap typically is defined by its location and triggering conditions, how hard it is to spot before it goes off, how much damage it deals, and whether or not the characters receive a saving throw to mitigate its effects. Traps that attack with arrows, sweeping blades, and other types of weaponry make normal attack rolls, with specific attack bonuses dictated by the trap’s design. A mechanical trap can be constructed by a PC through successful use of the Craft (traps) skill (see Designing a Trap and the Craft skill description).

Creatures that succeed on a Perception check detect a trap before it is triggered. The DC of this check depends on the trap itself. Success generally indicates that the creature has detected the mechanism that activates the trap, such as a pressure plate, odd gears attached to a door handle, and the like. Beating this check by 5 or more also gives some indication of what the trap is designed to do.

Magic

Many spells can be used to create dangerous traps. Unless the spell or item description states otherwise, assume the following to be true.

• A successful Perception check (DC 25 + spell level) detects a magic trap before it goes off.
• Magic traps permit a saving throw in order to avoid the effect (DC 10 + spell level × 1.5).
• Magic traps may be disarmed by a character with the trapfinding class feature with a successful Disable Device skill check (DC 25 + spell level). Other characters have no chance to disarm a magic trap with a Disable Device check.

Magic traps are further divided into spell traps and magic device traps. Magic device traps initiate spell effects when activated, just as wands, rods, rings, and other magic items do. Creating a magic device trap requires the Craft Wondrous Item feat.

Spell traps are simply spells that themselves function as traps. Creating a spell trap requires the services of a character who can cast the needed spell or spells, who is usually either the character creating the trap or an NPC spellcaster hired for that purpose.

Perception and Disable Device DCs

The builder sets the Perception and Disable Device DCs for a mechanical trap. For a magic trap, the values depend on the highest-level spell used.

Mechanical Trap

The base DC for both Perception and Disable Device checks is 20. Raising or lowering either of these DCs affects the CR (Table: CR Modifiers for Mechanical Traps).

Magic Trap

The DC for both Perception and Disable Device checks is equal to 25 + the spell level of the highest-level spell used. Only characters with the trapfinding class feature can attempt a Disable Device check involving a magic trap.

Trigger

A trap’s trigger determines how it is sprung.

Location

A location trigger springs a trap when someone stands in a particular square.

Proximity

This trigger activates the trap when a creature approaches within a certain distance of it. A proximity trigger differs from a location trigger in that the creature need not be standing in a particular square. Creatures that are flying can spring a trap with a proximity trigger but not one with a location trigger. Mechanical proximity triggers are extremely sensitive to the slightest change in the air. This makes them useful only in places such as crypts, where the air is unusually still.

The proximity trigger used most often for magic device traps is the alarm spell. Unlike when the spell is cast, an alarm spell used as a trigger can have an area that’s no larger than the area the trap is meant to protect.

Some magic device traps have special proximity triggers that activate only when certain kinds of creatures approach. For example, a detect good spell can serve as a proximity trigger on an evil altar, springing the attached trap only when someone of good alignment gets close enough to it.

Sound

This trigger springs a magic trap when it detects any sound. A sound trigger functions like an ear and has a +15 bonus on Perception checks. A successful Stealth check, magical silence , and other effects that would negate hearing defeat it. A trap with a sound trigger requires the casting of clairaudience during its construction.

Visual

This trigger for magic traps works like an actual eye, springing the trap whenever it “sees” something. A trap with a visual trigger requires the casting of arcane eye, clairvoyance , or true seeing during its construction. Sight range and the Perception bonus conferred on the trap depend on the spell chosen, as shown.

Spell

Touch

A touch trigger, which springs the trap when touched, is one of the simplest kinds of trigger to construct. This trigger may be physically attached to the part of the mechanism that deals the damage or it may not. You can make a magic touch trigger by adding alarm to the trap and reducing the area of the effect to cover only the trigger spot.

Timed

This trigger periodically springs the trap after a certain duration has passed.

Spell

All spell traps have this kind of trigger. The appropriate spell descriptions explain the trigger conditions for traps that contain spell triggers.

Duration

Unless otherwise stated, most traps have a duration of instantaneous; once triggered, they have their effect and then stop functioning. Some traps have a duration measured in rounds. Such traps continue to have their listed effect each round at the top of the initiative order (or whenever they were activated, if they were triggered during combat).

Reset

A reset element is the set of conditions under which a trap becomes ready to trigger again. Resetting a trap usually takes only a minute or so. For a trap with a more difficult reset method, you should set the time and labor required.

No Reset

Short of completely rebuilding the trap, there’s no way to trigger it more than once. Spell traps have no reset element.

Repair

To get the trap functioning again, you must repair it. Repairing a mechanical trap requires a Craft (traps) check against a DC equal to the one for building it. The cost for raw materials is one-fifth of the trap’s original market price. To calculate how long it takes to fix a trap, use the same calculations you would for building it, but use the cost of the raw materials required for repair in place of the market price.

Manual

Resetting the trap requires someone to move the parts back into place. This is the kind of reset element most mechanical traps have.

Automatic

The trap resets itself, either immediately or after a timed interval.

Bypass (Optional Element)

If the builder of a trap wants to be able to move past the trap after it is created or placed, it’s a good idea to build in a bypass mechanism: something that temporarily disarms the trap. Bypass elements are typically used only with mechanical traps; spell traps usually have built-in allowances for the caster to bypass them.

Lock

A lock bypass requires a DC 30 Disable Device check to open.

Hidden Switch

A hidden switch requires a DC 25 Perception check to locate.

Hidden Lock

A hidden lock combines the features above, requiring a DC 25 Perception check to locate and a DC 30 Disable Device check to open.

Effect

The effect of a trap is what happens to those who spring it. This often takes the form of either damage or a spell effect, but some traps have special effects. A trap usually either makes an attack roll or forces a saving throw to avoid it. Occasionally a trap uses both of these options, or neither (see Never Miss).

Pits

These are holes (covered or not) that characters can fall into, causing them to take damage. A pit needs no attack roll, but a successful Reflex save (DC set by the builder) avoids it. Other save-dependent mechanical traps also fall into this category. Falling into a pit deals 1d6 points of damage per 10 feet of depth.

Pits in dungeons come in three basic varieties: uncovered, covered, and chasms. Pits and chasms can be defeated by judicious application of the Acrobatics skill, the Climb skill, or various mechanical or magical means.

Uncovered pits and natural chasms serve mainly to discourage intruders from going a certain way, although they cause much grief to characters who stumble into them in the dark, and they can greatly complicate nearby melee.

Covered pits are much more dangerous. They can be detected with a DC 20 Perception check, but only if the character is taking the time to carefully examine the area before walking across it. A character who fails to detect a covered pit is still entitled to a DC 20 Reflex save to avoid falling into it. If she was running or moving recklessly at the time, however, she gets no saving throw and falls automatically.

Trap coverings can be as simple as piled refuse (straw, leaves, sticks, garbage), a large rug, or an actual trap door concealed to appear as a normal part of the floor. Such a trap door usually swings open when enough weight (usually about 50 to 80 pounds) is placed upon it. Devious trap builders sometimes design trap doors so they spring back shut after they open. The trap door might lock once it’s back in place, leaving the stranded character well and truly trapped. Opening such a trap door is just as difficult as opening a regular door (assuming the trapped character can reach it), and a DC 13 Strength check is needed to keep a spring-loaded door open.

Pit traps often have something nastier than just a hard floor at the bottom. A trap designer might put spikes, monsters, or a pool of acid, lava, or even water at the bottom. For rules on pit spikes and other such add-ons, see the Miscellaneous Trap Features section.

Monsters sometimes live in pits. Any monster that can fit into the pit might have been placed there by the dungeon’s designer, or might simply have fallen in and not been able to climb back out.

A secondary trap, mechanical or magical, at the bottom of a pit can be particularly deadly. Activated by a falling victim, the secondary trap attacks the already injured character when she’s least ready for it.

Ranged Attack Traps

These traps fling darts, arrows, spears, or the like at whomever activated the trap. The builder sets the attack bonus. A ranged attack trap can be configured to simulate the effect of a composite bow with a high Strength rating, which provides the trap with a bonus on damage equal to its Strength rating. These traps deal whatever damage their ammunition normally does. If a trap is constructed with a high Strength rating, it has a corresponding bonus on damage.

Melee Attack Traps

These traps feature such obstacles as sharp blades that emerge from walls and stone blocks that fall from ceilings. Once again, the builder sets the attack bonus. These traps deal the same damage as the melee weapons they “wield.” In the case of a falling stone block, you can assign any amount of bludgeoning damage you like, but remember that whoever resets the trap has to lift that stone back into place.

A melee attack trap can be constructed with a built-in bonus on damage rolls, just as if the trap itself had a high Strength score.

Spell Traps

Spell traps produce the spell’s effect. Like all spells, a spell trap that allows a saving throw has a save DC of 10 + spell level + caster’s relevant ability modifier.

Magic Device Traps

These traps produce the effects of any spells included in their construction, as described in the appropriate entries. If the spell in a magic device trap allows a saving throw, its save DC is (10 + spell level) × 1.5. Some spells make attack rolls instead.

Special

Some traps have miscellaneous features that produce special effects, such as drowning for a water trap or ability damage for poison. Saving throws and damage depend on the poison or are set by the builder, as appropriate.

Miscellaneous Trap Features

Some traps include optional features that can make them considerably more deadly. The most common features are discussed below.

Alchemical Item

Mechanical traps might incorporate alchemical devices or other special substances or items, such as tanglefoot bags, alchemist’s fire, thunderstones, and the like. Some such items mimic spell effects. If the item mimics a spell effect, it increases the CR as shown on Table: CR Modifiers for Mechanical Traps: CR Modifiers for Mechanical Traps.

Gas

With a gas trap, the danger is in the inhaled poison it delivers. Traps employing gas usually have the never miss and onset delay features.

Liquid

Any trap that involves a danger of drowning is in this category. Traps employing liquid usually have the never miss and onset delay features.

Multiple Targets

Traps with this feature can affect more than one character.

Never Miss

When the entire dungeon wall moves to crush you, your quick reflexes won’t help, since the wall can’t possibly miss. A trap with this feature has neither an attack bonus nor a saving throw to avoid, but it does have an onset delay. Most traps involving liquid or gas are of the never miss variety.

Onset Delay

An onset delay is the amount of time between when the trap is sprung and when it deals damage. A never miss trap always has an onset delay.

Poison

Traps that employ poison are deadlier than their nonpoisonous counterparts, so they have correspondingly higher CRs. To determine the CR modifier for a given poison, consult Table: CR Modifiers for Mechanical Traps. Only injury, contact, and inhaled poisons are suitable for traps; ingested types are not. Some traps simply deal the poison’s damage. Others deal damage with ranged or melee attacks as well.

Pit Spikes

Treat spikes at the bottom of a pit as daggers, each with a +10 attack bonus. The damage bonus for each spike is +1 per 10 feet of pit depth (to a maximum of +5). Each character who falls into the pit is attacked by 1d4 spikes. This damage is in addition to any damage from the fall itself, and the statistics presented above are merely the most common variant–some traps might have far more dangerous spikes at their bottom. Pit spikes add to the average damage of the trap (see Average Damage, below).

Pit Bottom

If something other than spikes waits at the bottom of a pit, it’s best to treat that as a separate trap (see Multiple Traps) with a location trigger that activates on any significant impact, such as a falling character.

Touch Attack

This feature applies to any trap that needs only a successful touch attack (melee or ranged) to hit.

Sample Traps

The following sample traps represent just some of the possibilities when constructing traps to challenge the player characters. (The 32 named sample traps in the core rulebook, such as Arrow Trap, Pit Trap, Poisoned Dart Trap, Swinging Axe Trap, and Fireball Trap, are presented as structured stat blocks rather than prose descriptions, so their full mechanical writeups are deferred to a future data batch. The trap-design guidelines below are fully covered.)

Designing a Trap

Designing new traps is a simple process. Start by deciding what type of trap you want to create.

Table: CR Modifiers for Mechanical Traps

Table: CR Modifiers for Magic Traps

Table: Cost Modifiers for Magic Device Traps

Table: Craft DCs (Traps)

Mechanical Traps

Simply select the elements you want the trap to have and add up the adjustments to the trap’s Challenge Rating that those elements require (see Table: CR Modifiers for Mechanical Traps) to arrive at the trap’s final CR. From the CR you can derive the DC of the Craft (traps) checks a character must make to construct the trap.

Magic Traps

As with mechanical traps, decide what elements you want and then determine the CR of the resulting trap (see CR Modifiers for Magic Traps). If a player character wants to design and construct a magic trap, he, or an ally, must have the Craft Wondrous Item feat. In addition, he must be able to cast the spell or spells that the trap requires–or he must be able to hire an NPC to cast the spells for him.

Challenge Rating of a Trap

To calculate the Challenge Rating of a trap, add all the CR modifiers (see Table: CR Modifiers for Mechanical Traps or CR Modifiers for Magic Traps) to the base CR for the trap type.

Mechanical Trap

The base CR for a mechanical trap is 0. If your final CR is 0 or lower, add features until you get a CR of 1 or higher.

Magic Trap

For a spell trap or magic device trap, the base CR is 1. The highest-level spell used modifies the CR (see CR Modifiers for Magic Traps).

Average Damage

If a trap (mechanical or magical) does hit point damage, calculate the average damage for a successful hit and round that value to the nearest multiple of 10. If the trap is designed to hit more than one target, multiply this value by 2. If the trap is designed to deal damage over a number of rounds, multiply this value by the number of rounds the trap will be active (or the average number of rounds, if the duration is variable). Use this value to adjust the Challenge Rating of the trap, as indicated on Table: CR Modifiers for Mechanical Traps. Damage from poison does not count toward this value, but extra damage from pit spikes and multiple attacks does.

For a magic trap, only one modifier applies to the CR–either the level of the highest-level spell used in the trap, or the average damage figure, whichever is larger.

Multiple Traps

If a trap is really two or more connected traps that affect approximately the same area, determine the CR of each one separately.

Multiple Dependent Traps

If one trap depends on the success of the other (that is, you can avoid the second trap by not falling victim to the first), characters earn XP for both traps by defeating the first one, regardless if the second one is also sprung.

Multiple Independent Traps

If two or more traps act independently (they do not depend on one another to activate), characters only earn XP for traps that they defeat.

Mechanical Trap Cost

The cost of a mechanical trap is 1,000 gp × the trap’s Challenge Rating. If the trap uses spells in its trigger or reset, add those costs separately. If the trap cannot be reset, divide the cost in half. If the trap has an automatic reset, increase the cost by half (+50%). Particularly simple traps, such as pit traps, might have a greatly reduced cost, subject to GM discretion. Such traps might cost as little as 250 gp × the trap’s Challenge Rating.

After you’ve determined the cost by Challenge Rating, add the price of any alchemical items or poison you incorporated into the trap. If the trap uses one of these elements and has an automatic reset, multiply the poison or alchemical item cost by 20 to provide an adequate supply of doses.

Multiple Traps

If a trap is really two or more connected traps, determine the final cost of each separately, then add those values together. This holds for both multiple dependent and multiple independent traps.

Magic Device Trap Cost

Building a magic device trap involves the expenditure of gp and requires the services of a spellcaster. Table: Cost Modifiers for Magic Device Traps summarizes the cost information for magic device traps. If the trap uses more than one spell (for instance, a sound or visual trigger spell in addition to the main spell effect), the builder must pay for them all (except alarm , which is free unless it must be cast by an NPC).

The costs derived from Table: Cost Modifiers for Magic Device Traps assume that the builder is casting the necessary spells himself (or perhaps some other PC is providing the spells for free). If an NPC spellcaster must be hired to cast them, those costs must be factored in as well (see Equipment).

A magic device trap takes 1 day to construct per 500 gp of its cost.

Spell Trap Cost

A spell trap has a cost only if the builder must hire an NPC spellcaster to cast it.

Craft DCs for Mechanical Traps

Once you know the Challenge Rating of a trap, determine the Craft (traps) DC by referring to the values and modifiers given on Table: Craft (Traps) DCs.

Making the Checks

To determine how much progress a character makes on building a trap each week, that character makes a Craft (traps) check. See the Craft skill description for details on Craft checks and the circumstances that can affect them.