See also: Dungeon Deathtraps
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.
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.
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.
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.
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||Sight Range||Perception Bonus|
|arcane eye||Line of sight (unlimited range)||+20|
|clairvoyance||One preselected location||+15|
|true seeing||Line of sight (up to 120 ft.)||+30|
If you want the trap to see in the dark, you must either choose the true seeing option or add darkvision to the trap as well. (Darkvision limits the trap’s sight range in the dark to 60 feet.) If invisibility, disguises, or illusions can fool the spell being used, they can fool the visual trigger as well.
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.
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).
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.
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.
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.
Mundane and magical traps can incorporate technological elements in their construction. Computers and AIs can also be connected to traps, allowing them to selectively trigger the traps remotely. Traps that incorporate technology gain the technological type, in addition to their normal type (see the following examples). The following technological triggers are available to traps.
Electric Eyes: Similar to a visual trigger, the trap incorporates a camera or other visual and audio recording device. Electric eyes typically have darkvision to a range of 120 feet, low-light vision, and a Perception bonus of +15. This trigger adds +1 to the trap’s CR and +5 to its crafting DC.
Genetic: A genetic trigger works in a fashion similar to scent. It can be set to target or not target living creatures within 30 feet (adjusted by wind as for scent) based on an individual, close family, or species relationship. For example, a trap could be set to target orcs, or to not target an NPC and his close relations. Genetic triggers are used in conjunction with other triggers and limit the maximum range of those triggers. A trap can incorporate up to half its CR in different genetic samples and conditions. This trigger adds +1 to the trap’s CR and +5 to its crafting DC.
|Concealed Laser Turret||CR 4|
Type mechanical and technological; Trigger camera (Perception +15); Reset automatic (1 round)
|Proximity Mine||CR 5|
Type mechanical and technological; Trigger genetic, proximity; Reset none
one grenade worth 1,000 gp or less, multiple targets and saves (see grenade rules)
|Electrified Door||CR 11|
Type mechanical and technological; Trigger touch (see text); Reset automatic (1 minute; see text)
10d8 electricity damage (Reflex DC 25 half) to anyone touching the door; typically an electrified door triggers only if a creature attempts to bypass or force the door; electrified doors connected to a generator have no charge limit, otherwise the trap has only enough energy to function once with no reset