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Traps

Traps can be found almost anywhere. One wrong step in an ancient tomb might trigger a series of scything blades, which cleave through armor and bone. The seemingly innocuous vines that hang over a cave entrance might grasp and choke anyone who pushes through them. A net hidden among the trees might drop on travelers who pass underneath. In a fantasy game, unwary adventurers can fall to their deaths, be burned alive, or fall under a fusillade of poisoned darts.

A trap can be either mechanical or magical in nature. Mechanical traps include pits, arrow traps, falling blocks, water-filled rooms, whirling blades, and anything else that depends on a mechanism to operate. Magic traps are either magical device traps or spell traps. Magical device traps initiate spell effects when activated. Spell traps are spells such as glyph of warding and symbol that function as traps.

Traps in Play

When adventurers come across a trap, you need to know how the trap is triggered and what it does, as well as the possibility for the characters to detect the trap and to disable or avoid it.

Triggering a Trap

Most traps are triggered when a creature goes somewhere or touches something that the trap’s creator wanted to protect. Common triggers include stepping on a pressure plate or a false section of floor, pulling a trip wire, turning a doorknob, and using the wrong key in a lock. Magic traps are often set to go off when a creature enters an area or touches an object. Some magic traps (such as the glyph of warding spell) have more complicated trigger conditions, including a password that prevents the trap from activating.

Detecting and Disabling a Trap

Usually, some element of a trap is visible to careful inspection. Characters might notice an uneven flagstone that conceals a pressure plate, spot the gleam of light off a trip wire, notice small holes in the walls from which jets of flame will erupt, or otherwise detect something that points to a trap’s presence.

A trap’s description specifies the checks and DCs needed to detect it, disable it, or both. A character actively looking for a trap can attempt a Wisdom (Perception) check against the trap’s DC. You can also compare the DC to detect the trap with each character’s passive Wisdom (Perception) score to determine whether anyone in the party notices the trap in passing. If the adventurers detect a trap before triggering it, they might be able to disarm it, either permanently or long enough to move past it. You might call for an Intelligence (Investigation) check for a character to deduce what needs to be done, followed by a Dexterity check using thieves’ tools to perform the necessary sabotage.

Any character can attempt an Intelligence (Arcana) check to detect or disarm a magic trap, in addition to any other checks noted in the trap’s description. The DCs are the same regardless of the check used. In addition, dispel magic has a chance of disabling most magic traps. A magic trap’s description provides the DC for the ability check made when you use dispel magic.

In most cases, a trap’s description is clear enough that you can adjudicate whether a character’s actions locate or foil the trap. As with many situations, you shouldn’t allow die rolling to override clever play and good planning. Use your common sense, drawing on the trap’s description to determine what happens. No trap’s design can anticipate every possible action that the characters might attempt.

You should allow a character to discover a trap without making an ability check if an action would clearly reveal the trap’s presence. For example, if a character lifts a rug that conceals a pressure plate, the character has found the trigger and no check is required.

Foiling traps can be a little more complicated. Consider a trapped treasure chest. If the chest is opened without first pulling on the two handles set in its sides, a mechanism inside fires a hail of poison needles toward anyone in front of it. After inspecting the chest and making a few checks, the characters are still unsure if it’s trapped. Rather than simply open the chest, they prop a shield in front of it and push the chest open at a distance with an iron rod. In this case, the trap still triggers, but the hail of needles fires harmlessly into the shield.

Traps are often designed with mechanisms that allow them to be disarmed or bypassed. Intelligent monsters that place traps in or around their lairs need ways to get past those traps without harming themselves. Such traps might have hidden levers that disable their triggers, or a secret door might conceal a passage that goes around the trap.

Trap Effects

The effects of traps can range from inconvenient to deadly, making use of elements such as arrows, spikes, blades, poison, toxic gas, blasts of fire, and deep pits. The deadliest traps combine multiple elements to kill, injure, contain, or drive off any creature unfortunate enough to trigger them. A trap’s description specifies what happens when it is triggered.

The attack bonus of a trap, the save DC to resist its effects, and the damage it deals can vary depending on the trap’s severity. Use the Trap Save DCs and Attack Bonuses table and the Damage Severity by Level table for suggestions based on three levels of trap severity.

A trap intended to be a setback is unlikely to kill or seriously harm characters of the indicated levels, whereas a dangerous trap is likely to seriously injure (and potentially kill) characters of the indicated levels. A deadly trap is likely to kill characters of the indicated levels.

Table: Trap Save DCs and Attack Bonuses
Trap Danger Save DC Attack Bonus
Setback 10–11 +3 to +5
Dangerous 12–15 +6 to +8
Deadly 16–20 +9 to +12
Table: Damage Severity by Level
Character Level Setback Dangerous Deadly
1st–4th 1d10 2d10 4d10
5th–10th 2d10 4d10 10d10
11th–16th 4d10 10d10 18d10
17th–20th 10d10 18d10 24d10

Complex Traps

Complex traps work like standard traps, except once activated they execute a series of actions each round. A complex trap turns the process of dealing with a trap into something more like a combat encounter.

When a complex trap activates, it rolls initiative. The trap’s description includes an initiative bonus. On its turn, the trap activates again, often taking an action. It might make successive attacks against intruders, create an effect that changes over time, or otherwise produce a dynamic challenge. Otherwise, the complex trap can be detected and disabled or bypassed in the usual ways.

For example, a trap that causes a room to slowly flood works best as a complex trap. On the trap’s turn, the water level rises. After several rounds, the room is completely flooded.

Sample Traps

The magical and mechanical traps presented here vary in deadliness and are presented in alphabetical order.

Animated Fresco (3pp)

Source TM

Magic trap

A horrible fresco animates, causing all who can see it to make a DC 18 Wisdom saving throw. Those who fail drop whatever they are holding and become frightened for up to one minute. While frightened, a creature must take the dash action and move away from the fresco by the safest available route, unless there is nowhere to move. A creature who ends its turn in a location where it does not have line of sight to the fresco may make a DC 18 Wisdom saving throw, ending the effect on a success. After animating, the fresco cannot animate again for 24 hours.

Animate Objects Trap (3pp)

Source TM

Magical trap

When one or more creatures enter the trapped region, up to 11 small or 5 medium weapons animate and attack them. On initiative 10, each weapon moves up to 30 feet towards a target and makes a melee weapon attack against a target within 5 feet at +6 to hit. Small weapons do 5 (1d6 + 2) slashing or piercing (as appropriate) damage on a hit while medium ones do 8 (1d10 + 3). Each weapon has AC 14 and is destroyed if it takes 18 hit points of damage. They are immune to necrotic, poison, and psychic damage. Casting dispel magic on a weapon causes it to revert to an inanimate state for one hour.

Collapsing Roof

Mechanical trap

This trap uses a trip wire to collapse the supports keeping an unstable section of a ceiling in place.

The trip wire is 3 inches off the ground and stretches between two support beams. The DC to spot the trip wire is 10. A successful DC 15 Dexterity check using thieves’ tools disables the trip wire harmlessly. A character without thieves’ tools can attempt this check with disadvantage using any edged weapon or edged tool. On a failed check, the trap triggers.

Anyone who inspects the beams can easily determine that they are merely wedged in place. As an action, a character can knock over a beam, causing the trap to trigger.

The ceiling above the trip wire is in bad repair, and anyone who can see it can tell that it’s in danger of collapse.

When the trap is triggered, the unstable ceiling collapses. Any creature in the area beneath the unstable section must succeed on a DC 15 Dexterity saving throw, taking 22 (4d10) bludgeoning damage on a failed save, or half as much damage on a successful one. Once the trap is triggered, the floor of the area is filled with rubble and becomes difficult terrain.

Commanding Visage (3pp)

Source TM

Magic trap

When a creature approaches within 10 feet of this large stone visage, it commands the creature to drink a potion of poison lying on the pedestal. The target of the command must make a successful DC 16 Wisdom saving throw or attempt to comply with it. A creature that succeeds on the saving throw is immune from further commands from this face.

There is a 50% probability that the stone face has 100 gp gems for eyes.

Crossbow Trap (3pp)

Source TM

Mechanical trap

When a creature steps on a pressure plate with more than 20 lbs. of force, or trips another type of proximity trigger, 1d6 crossbows make a ranged attack at +8 to hit at random creatures within a 10 foot by foot area around the trigger. A target that is hit takes 4 (1d8) piercing damage per hit.

The crossbows are hidden in the walls and usually concealed by wooden paneling. The DC to spot them is 16. Locating the trigger requires a DC 18 Intelligence (Investigation) check. The trap can be disabled by wedging the pressure plate or blocking the bolt holes.

Disembodied Hands with Chilling Touch (3pp)

Source TM

Magic trap

When a creature enters a room being guarded by this trap, a pair of spectral hands appear and target it. Up to six pairs of hands may appear, one per creature in the area. On initiative 20, the hands move up to 50 feet to follow their target as long as the target is within the room, and make a spell attack against their target if they are within 10 feet of the target.

The attack is made at +7 to hit. On a successful hit, the target takes 3 (1d6) cold damage and, on a failed DC 15 Constitution saving throw, loses 1 point of Strength until completing a long rest.

Disembodied Hands with Vampiric Touch (3pp)

Source TM

Magical trap

When a creature enters a room being guarded by this trap, a pair of spectral hands appear and target it. Up to six pairs of hands may appear, one per creature in the area. On initiative 20, the hands move up to 50 feet to follow their target as long as the target is within the room, and make a spell attack against their target if they are within 10 feet of the target. The attack is made at +7 to hit. On a successful hit, the target takes 14 (4d6) necrotic damage and cannot regain hit points until the start of the next round.

Falling Net

Mechanical trap

This trap uses a trip wire to release a net suspended from the ceiling.

The trip wire is 3 inches off the ground and stretches between two columns or trees. The net is hidden by cobwebs or foliage. The DC to spot the trip wire and net is 10. A successful DC 15 Dexterity check using thieves’ tools breaks the trip wire harmlessly. A character without thieves’ tools can attempt this check with disadvantage using any edged weapon or edged tool. On a failed check, the trap triggers.

When the trap is triggered, the net is released, covering a 10-foot-square area. Those in the area are trapped under the net and restrained, and those that fail a DC 10 Strength saving throw are also knocked prone. A creature can use its action to make a DC 10 Strength check, freeing itself or another creature within its reach on a success. The net has AC 10 and 20 hit points. Dealing 5 slashing damage to the net (AC 10) destroys a 5-foot-square section of it, freeing any creature trapped in that section.

Falling Stone Blocks (3pp)

Source TM

Mechanical trap

When a creature steps on a pressure plate with more than 20 lbs of force (or, in the case of weak construction, causes a large vibration by, for example, casting thunder wave), several stone blocks fall from the ceiling in a 10-foot radius around the creature. Each creature within the circle must make a DC 15 Dexterity saving throw. Those who fail the saving throw take 18 (4d8) bludgeoning damage while those who succeed take half this amount. The unstable state of the ceiling can be identified with a successful DC 14 Intelligence (Investigation) check.

Finding the pressure plate requires a DC 15 Wisdom (Perception) check.

Fire-Breathing Statue

Magic trap

This trap is activated when an intruder steps on a hidden pressure plate, releasing a magical gout of flame from a nearby statue. The statue can be of anything, including a dragon or a wizard casting a spell.

The DC is 15 to spot the pressure plate, as well as faint scorch marks on the floor and walls. A spell or other effect that can sense the presence of magic, such as detect magic, reveals an aura of evocation magic around the statue.

The trap activates when more than 20 pounds of weight is placed on the pressure plate, causing the statue to release a 30-foot cone of fire. Each creature in the fire must make a DC 13 Dexterity saving throw, taking 22 (4d10) fire damage on a failed save, or half as much damage on a successful one.

Wedging an iron spike or other object under the pressure plate prevents the trap from activating. A successful dispel magic (DC 13) cast on the statue destroys the trap.

Fire Breathing Suit of Armor (3pp)

Source TM

Magic trap

When a creature comes within fifteen feet of the armor, the armor releases a 15-foot cone of fire. Each creature within the cone must make a DC 16 Dexterity saving throw. Those that fail take 17 (4d6) damage while those that succeed take half as much.

The trap recharges on a 5 or 6 on 1d6. A variant of this trap is a fireplace breathing sparks instead.

Hypnotic Brazier (3pp)

Source TM

Magic trap

This brazier may stand in something resembling an elaborate ritual chamber – with candles, diagrams, tapestries and idols. Its magical flames create a hypnotic pattern. Any creature that looks upon it must succeed on a DC 16 Wisdom saving throw or be hypnotized by the brazier. A hypnotized creature may attempt a new saving throw at the end of each its turns. Once it has succeeded on a saving throw, the creature is immune to the brazier’s hypnosis for 24 hours. A hypnotized creature makes every effort to get amidst the brazier’s flames as quickly as possible. Each round that a creature spends in the fire it takes 27 (6d8) fire damage. Dispel magic cast with a level 4 spell slot dampens the hypnotic pattern for 1 round, giving any creatures needing to make a saving throw advantage.

Magic Mouth (3pp)

Source TM

Magic trap

When a creature comes within 30 feet of the magic mouth, it cries loudly for help. Make three random monster checks. The magic mouth then becomes inactive for one hour. A variant of this trap also casts arcane lock on all exits, increasing the DC to break them down or unlock them by 10.

Malevolent Mirage (3pp)

Source TM

Magic trap

A wondrous hypnotic illusion appears. Any creature seeing the illusion must make a DC 16 Wisdom saving throw or use its movement and make the dash action to enter its area. Within the area covered by the illusion may be spiked pits, fire, or any other form of dangerous area. The illusion can be seen through with a successful DC 18 Intelligence (Investigation) check.

The mirage could originate from an idol, fresco, statue, gemstone (1d3 x 100 gp), etc.

Moving Executioner Statue (3pp)

Source TM

Mechanical trap

If a creature comes within 5 feet of the statue without depressing the bypass switch to disarm it, the statue makes a melee attack at +10 to hit against it. On a hit, the target takes 15 (2d6 + 8) slashing damage. The statue continues to make attacks as long as a target is within range and the statue has not been destroyed or disarmed. The bypass switch can be located with a successful DC 18 Wisdom (Perception) check. The statue is destroyed if it takes 25 points of damage. It has an AC of 15. The statue may guard a pedestal with small gemstones of little value, or stand in a room resembling a shrine or temple.

Pits

Mechanical trap

Four basic pit traps are presented here.

Simple Pit. A simple pit trap is a hole dug in the ground. The hole is covered by a large cloth anchored on the pit’s edge and camouflaged with dirt and debris. The DC to spot the pit is 10. Anyone stepping on the cloth falls through and pulls the cloth down into the pit, taking damage based on the pit’s depth (usually 10 feet, but some pits are deeper).

Hidden Pit. This pit has a cover constructed from material identical to the floor around it. A successful DC 15 Wisdom (Perception) check discerns an absence of foot traffic over the section of floor that forms the pit’s cover. A successful DC 15 Intelligence (Investigation) check is necessary to confirm that the trapped section of floor is actually the cover of a pit. When a creature steps on the cover, it swings open like a trapdoor, causing the intruder to spill into the pit below. The pit is usually 10 or 20 feet deep but can be deeper. Once the pit trap is detected, an iron spike or similar object can be wedged between the pit’s cover and the surrounding floor in such a way as to prevent the cover from opening, thereby making it safe to cross. The cover can also be magically held shut using the arcane lock spell or similar magic.

Locking Pit. This pit trap is identical to a hidden pit trap, with one key exception: the trap door that covers the pit is spring-loaded. After a creature falls into the pit, the cover snaps shut to trap its victim inside. A successful DC 20 Strength check is necessary to pry the cover open. The cover can also be smashed open. A character in the pit can also attempt to disable the spring mechanism from the inside with a DC 15 Dexterity check using thieves’ tools, provided that the mechanism can be reached and the character can see. In some cases, a mechanism (usually hidden behind a secret door nearby) opens the pit.

Spiked Pit. This pit trap is a simple, hidden, or locking pit trap with sharpened wooden or iron spikes at the bottom. A creature falling into the pit takes 11 (2d10) piercing damage from the spikes, in addition to any falling damage. Even nastier versions have poison smeared on the spikes. In that case, anyone taking piercing damage from the spikes must also make a DC 13 Constitution saving throw, taking an 22 (4d10) poison damage on a failed save, or half as much damage on a successful one.

Poison Darts

Mechanical trap

When a creature steps on a hidden pressure plate, poison-tipped darts shoot from spring-loaded or pressurized tubes cleverly embedded in the surrounding walls. An area might include multiple pressure plates, each one rigged to its own set of darts.

The tiny holes in the walls are obscured by dust and cobwebs, or cleverly hidden amid bas-reliefs, murals, or frescoes that adorn the walls. The DC to spot them is 15. With a successful DC 15 Intelligence (Investigation) check, a character can deduce the presence of the pressure plate from variations in the mortar and stone used to create it, compared to the surrounding floor. Wedging an iron spike or other object under the pressure plate prevents the trap from activating. Stuffing the holes with cloth or wax prevents the darts contained within from launching.

The trap activates when more than 20 pounds of weight is placed on the pressure plate, releasing four darts. Each dart makes a ranged attack with a +8 bonus against a random target within 10 feet of the pressure plate (vision is irrelevant to this attack roll). (If there are no targets in the area, the darts don’t hit anything.) A target that is hit takes 2 (1d4) piercing damage and must succeed on a DC 15 Constitution saving throw, taking 11 (2d10) poison damage on a failed save, or half as much damage on a successful one.

Poison Needle

Mechanical trap

A poisoned needle is hidden within a treasure chest’s lock, or in something else that a creature might open. Opening the chest without the proper key causes the needle to spring out, delivering a dose of poison.

When the trap is triggered, the needle extends 3 inches straight out from the lock. A creature within range takes 1 piercing damage and 11 (2d10) poison damage, and must succeed on a DC 15 Constitution saving throw or be poisoned for 1 hour.

A successful DC 20 Intelligence (Investigation) check allows a character to deduce the trap’s presence from alterations made to the lock to accommodate the needle. A successful DC 15 Dexterity check using thieves’ tools disarms the trap, removing the needle from the lock. Unsuccessfully attempting to pick the lock triggers the trap.

Rapid Rot (3pp)

Source TM

Magic trap

A creature who touches the objet protected by this trap must make a successful DC 14 Charisma saving throw or it and all objects it is wearing or carrying instantly age 1000 years. For most creatures, this means instant death, leaving only grey, moldy dust remaining. Detecting the trap requires a successful DC 18 Intelligence (Arcana) check. Once the trap has triggered, it cannot do so again for 24 hours.

Note: This trap is always linked to an item of great worth (1d6 x 500 gp), usually prominently displayed and surrounded by grim reminders of death and decay. E.g. a solid gold bowl in a room full of graven stone skulls, dust and moldy cobwebs, held by the statue of Death personified.

Rolling Sphere

Mechanical trap

When 20 or more pounds of pressure are placed on this trap’s pressure plate, a hidden trapdoor in the ceiling opens, releasing a 10-foot-diameter rolling sphere of solid stone.

With a successful DC 15 Wisdom (Perception) check, a character can spot the trapdoor and pressure plate. A search of the floor accompanied by a successful DC 15 Intelligence (Investigation) check reveals variations in the mortar and stone that betray the pressure plate’s presence. The same check made while inspecting the ceiling notes variations in the stonework that reveal the trapdoor. Wedging an iron spike or other object under the pressure plate prevents the trap from activating.

Activation of the sphere requires all creatures present to roll initiative. The sphere rolls initiative with a +8 bonus. On its turn, it moves 60 feet in a straight line. The sphere can move through creatures’ spaces, and creatures can move through its space, treating it as difficult terrain. Whenever the sphere enters a creature’s space or a creature enters its space while it’s rolling, that creature must succeed on a DC 15 Dexterity saving throw or take 55 (10d10) bludgeoning damage and be knocked prone.

The sphere stops when it hits a wall or similar barrier. It can’t go around corners, but smart dungeon builders incorporate gentle, curving turns into nearby passages that allow the sphere to keep moving.

As an action, a creature within 5 feet of the sphere can attempt to slow it down with a DC 20 Strength check. On a successful check, the sphere’s speed is reduced by 15 feet. If the sphere’s speed drops to 0, it stops moving and is no longer a threat.

Room Full of Diseased Corpses (3pp)

Source TM

Magic trap

The corpses all have slimy doom. The disease can be recognized with a successful DC 15 Wisdom (Medicine) check. The corpses may be just piled up, or placed elaborately in wooden thrones, hung on hooks, sitting in plush chairs or any other arrangement. They are usually moldy and putrid, but some (25% probability) possess 1d3 pieces of jewelry, value 2d8 x 10 gp. Finding any treasure requires a DC 14 Wisdom (perception) check (and probably touching the corpses).

Scything Blade (3pp)

Source TM

Mechanical trap

Typically released by a trip wire, the scything blade can also be swung by a suit of armor. When the trigger is released, the scythe makes a melee weapon attack against a creature within 5 feet at +6 to hit. On a successful hit, it does 6 (1d8 + 2) slashing damage.

The trip wire can be noted with a DC 14 Wisdom (Perception) check and the trap can be disarmed by carefully cutting the wire. This requires a DC 12 Dexterity check and failing the check by five or more triggers the trap.

Sphere of Annihilation

Magic trap

Magical, impenetrable darkness fills the gaping mouth of a stone face carved into a wall. The mouth is 2 feet in diameter and roughly circular. No sound issues from it, no light can illuminate the inside of it, and any matter that enters it is instantly obliterated.

A successful DC 20 Intelligence (Arcana) check reveals that the mouth contains a sphere of annihilation that can’t be controlled or moved. It is otherwise identical to a normal sphere of annihilation.

Some versions of the trap include an enchantment placed on the stone face, such that specified creatures feel an overwhelming urge to approach it and crawl inside its mouth. This effect is otherwise like the sympathy aspect of the antipathy/sympathy spell. A successful dispel magic (DC 18) removes this enchantment.

Swinging Block (3pp)

Source TM

Mechanical trap

When, after placing more than 20 lbs of force on a pressure plate, a creature removes its weight from the plate, a large stone block swings across on metal chains. Any creature within 5 feet of the trigger must make a DC 15 Dexterity saving throw. On a failed saving throw, the creature takes 21 (6d6) bludgeoning damage. A creature that is moving normally feels the plate shift with a DC 18 Wisdom (Perception) check. If a creature is dashing when it steps on the plate, it has disadvantage on the check.

Disarming the trap once the trigger is detected requires a DC 18 Dexterity check with thieves’ tools.

Hazards

Hazards are not necessarily intentionally set to injure, harm, or delay creatures, but instead are usually naturally occurring phenomenon that do in fact either inconvenience or harm creatures. Hazards may include naturally collapsing ice or a wooden floor, or things like green slime or different types of molds that are sometimes found in subterrainean settings.

Brown Mold (3pp)

Source TM

Hazard

Mold is usually hidden in decaying garbs, on a decomposing corpse, a chest, a tapestry covering a wormeaten wardrobe, etc.

Green Slime (3pp)

Source TM

Hazard

Green slime may hang from the ceiling, fall from halfeaten furniture, be concealed in large ceramic pots, a fountain or disguised as a potion in a chest, etc.

Rot Grubs (3pp)

Source TM

Hazard

The bodies may be dead adventurers with a few useful items still on their bodies (20% probability), villagers or just random corpses.

Yellow Mold (3pp)

Source TM

Hazard

Mold is usually hidden in decaying garbs, on a decomposing corpse, a chest, a tapestry covering a worm-eaten wardrobe, etc.