Traps & Trapmaking

It’s A Trap!

(A Work In Progress) 

This is still being developed; there’s some editing I need to do on things like costs, damage values, and scavenging; honestly, it’s still in a semi-rough note stage. However, due to various time constraints, this site has gone too long without a meaningful update, so I felt an in-progress article was preferable to publishing nothing at all.

Dungeons & Dragons 4th edition is notably weak when it comes to doing things outside the formal structure of encounters or skill challenges. Virtually all game mechanics are designed to work in 5 minute blocks, except for some travel powers and a few other things. It also suffers from an attitude that anything which isn’t combat should be handwaved or made mechanic free. Also, Michael Longcor’s “Snare And Deadfall” randomly shuffled to the top on my iPod while I was taking my morning executive order. No, that’s not right. Morning constitutional. Sorry, these days, it’s hard to tell the difference. But I digress.

Anyway, the point of all that is… this article is about players making traps in 4e, as opposed to, say, the Endurance feat, which was a trap for players in 3e. Ba-dum-BUM.

Trapmaking Skills

Trapmaking is a martial practice.

Level: 5 Market Price: 100 gp
Time: Variable Key Skill: Dungeoneering, Thievery, or Nature
Duration: 24 hours or until used
Component Cost: 1 healing surge+special, see below

Use of this practice allows the character to make and place traps of various sorts. Such traps can be purely mechanical, or include magical elements in their making, according to the skills of the trapmaker and his party.

Generally, traps are used when the players have some situational advantage and time to prepare. If they have laid an ambush for an approaching patrol, or are defending a fortress against invaders, or are setting up for the night and wish to be alerted to intruders, they likely have both the time and opportunity to use traps. Some are simple enough to be set up in a few minutes, while others are more elaborate.


Generally, traps can be built from scavenged items. These are not intended to be masterpieces of engineering, just hastily improvised add-ons to the fight. Of course, sometimes, resources are limited. Traps have a “resource cost” which is listed in GP, for the sake of convenience.

Purchasing:“Trap Components” (a mix of wood, metal bits, grease, rope, and so on) can be purchased at any community of 100 or more, and these weigh 1 lb per 10 gp worth of junk.

Scavenging: Characters with the Nature or Dungeoneering skill can scavenge useful materials. Use the nature skill in wilderness or small village/farming town settings, and the dungeoneering skill underground or in larger cities. Scavenging is a moderate skill check. The level is set by the DM, based on the general encounter level, the character’s level, and the environment. A city slum full of cast-off junk is level 3 to 5: Anyone can scavenge there. Polar wastes with nothing but glacial ice are level 15 or more; it takes a skilled outdoorsman to spot the things he needs among the blinding drifts. A successful scavenging check yields 10 gp* skill check level worth of materials. If these materials are not used to make traps before the next encounter, they are lost and discarded. Each scavenge check takes 1d10 minutes, but players can reduce the time by 1 minute (never less than one) by taking a -2 penalty on their roll. Each scavenging check after the first increases the level of the skill check by 2. A failed scavenging check not only wastes time, it consumes a healing surge.

Recovering: Assuming there’s time after the encounter, during a short rest, the PCs can make Moderate checks on the same skills used to make traps to recover 50% of the materials. If the roll beats a Hard DC, they recover 75% instead.

Creating Traps

Creating a trap requires having enough component materials and rolling the appropriate skill. Once this is done, the trap is set. Depending on the nature of the trap, the character may be able to choose where to place it, or it may be limited to specific locations on the battlefield.

General Trap Notes And Rules

Specific exceptions to these rules will be noted in the trap descriptions.

  • Once placed, a trap cannot generally be moved.
  • Traps will normally trigger against anyone who meets the conditions; they cannot tell friend from foe.
  • Any trap not triggered within 24 hours of creation will cease to function.
  • The default Perception DC to notice a trap is  10+the trap creator’s skill modifier.
  • Traps attack Armor Class at trap level+5.
  • Traps attack Reflex, Will, or Fortitude at trap level +3.
  • The DC and skill needed to create a given trap is given in the trap description; the level of the check is based on the level of the trap being constructed.
  • Most traps are expended once they make their attack, hit or miss; those which aren’t are noted.

Because these traps are intended as tools for players to use against monsters, and not as challenges for players to overcome, the descriptions are considerably simpler.


Set up a pile of rocks. Wait until someone walks under them. Profit.

This trap can only be set where there’s a place to pile up heavy objects over a passage or open space someone can be expected to walkthrough. Generally, this means a wall, cliff face, or tall tree.

Level: 4,9, or 14 chosen by trapmaker, cannot be higher than trapmaker’s own level.

Check: Moderate Dungeoneering or Nature

Cost: 8 gp per level

Time to create: 20 minutes

Trigger: Entering the square (will target flyers passing below the rock). The trap can be rigged to go off automatically, or, it can be linked to a rope which can be pulled by someone within 5 squares as an immediate reaction to a target entering the trap area.

Attack: Reflex

Hit: 2d8+4 damage, increasing to 3d8+4 at 9th level and 4d8+6 at 14th level, and target is immobilized until escape (DC of trap’s level+12).

Special: The trap can be made larger, affecting a Burst 1 centered on the triggering square. This does half damage.

Jaw Trap

This classic trap consists of a pressure plate, some springs, and sharp metal jaws that clamp painfully on a limb.

Level: 5, 10, or 15 chosen by trapmaker, cannot be higher than trapmaker’s own level.

Check: Moderate Thievery

Cost: 8 gp per level

Time to create: 10 minutes

Trigger: Entering the square (does not target flyers)

Attack: Fortitude

Hit: The trap slams on the victim’s foot, doing 1d6+3 damage (2d6+5 at 10th level, 3d6+8 at 15th level). He is immobilized and takes ongoing 5 damage (save ends, cannot save while in the trap), increasing to ongoing 10 at 15th level. Escaping the trap requires an Escape action against a DC of 12+the trap’s level. This does not stop the ongoing damage. The victim can also expend a healing surge to free themselves as a minor action; this changes the ongoing effect to “Ongoing 5 (or 10) and slowed; save at -2 ends both”.

Special: An ally adjacent to the trap can make an Athletics or Thievery check against a DC of 12+the trap’s level to free the person held.

Pungee Stick

A favorite of many woodland dwellers dealing with enemies, this consists of a small pit lined with sharpened spikes, usually coated with poison. It can only be created where there is dirt or soil that can be relatively easily dug. (Magical rituals, mining gear, or unusual abilities might justify digging into stone)

Level: 2,7, or 12 chosen by trapmaker, cannot be higher than trapmaker’s own level.

Check: Moderate Nature

Cost: 4 gp per level, not including poison

Time to create: 15 minutes

Trigger: Entering the target square (does not target flyers)

Attack: Reflex

Hit: 1d6+2 damage, increasing to 1d6+5 at 7th level and 2d6+5 at 12th level, and target is immobilized (save ends). Aftereffect: Target is slowed (save ends). If the stakes were coated with poison, the poison attacks if the trap hits.

Special: This trap remains in the square. Any creature entering the square must either treat it as difficult terrain (walking carefully around the pit), or be attacked by the trap. This attack is at a -2. If the trap is poisoned and has not yet hit a target, the poison remains.


A snare is a simple loop of rope, attached to some sort of counterweight; when triggered, it will catch the victim and entangle them.

Level: 1,5, or 10, chosen by trapmaker, cannot be higher than trapmaker’s own level.

Check: Easy Nature

Cost: 5 gp per level

Time to create: 5 minutes

Trigger: Entering the square (does not target flyers)

Attack: Reflex

Hit: Target is immobilized and hanging upside down (he can be considered Prone, but gains no defense bonus against Area attacks; indeed, he has a -2 to Reflex defense.) An escape action against a DC of the trap’s level+12 will free him. He can gain a +4 on this check by taking a standard instead of a move action. Once freed, he can appear in the trap’s square or any empty adjacent square; a DC 10 Acrobatics check can be made to avoid being prone

Spike Flinger

This trap uses sharpened sticks, arrows, or other pointy things, along with something to propel them. It can be triggered by a pressure mechanism or by an observer. The trap has two components; the ‘danger zone’, where the spikes can attack, and the actual source of the spikes. There must be line of sight and effect from the source to the possible target squares.

Level: 5,10, or 15 chosen by trapmaker, cannot be higher than trapmaker’s own level.

Check: Moderate Dungeoneering or Thievery

Cost: 20 gp per level

Time to create: 20 minutes

Trigger: The target area consists of one square within 10 squares of the source. At level 10, it can include 4 squares which must be adjacent. At level 15, it can be built with some rotating parts, so it can target up to 6 squares which are not adjacent.

Attack: Armor Class

Hit: 2d6+5 damage, increasing to 2d6+9 at 10th level and 3d6+9 at 15th level, and target takes ongoing 5 damage (save ends), increasing to ongoing 10 damage at 15th level.

Options: Someone adjacent to the trap’s source can reload it as a move action. This can be done once at 5th level, twice at 10th, and three times at 15th.

Special: The launcher can be attacked separately from the trap. It has AC 12, Resist 5 (All),  and hit points equal to 4*level.

Swinging Weight

This takes a bit of work to prepare, and requires a high point at least four squares above the target area and at least two squares away. It consists of a trigger system and a lot of heavy material (rocks, metal bits, tree trunks), attached to a swinging rope.

Level: 8,13, or 18 chosen by trapmaker, cannot be higher than trapmaker’s own level.

Check: Moderate Nature or Dungeoneering

Cost: 20 gp per level

Time to create: 25 minutes

Trigger: Entering the target square (does not target flyers)

Attack: Reflex

Hit: 3d6+4 damage, increasing to 4d6+6 at 13th level and 5d6+8 at 18th level, and target is pushed 3 squares and knocked prone. (The direction of the push depends on where the weight is swinging from, relative to the origin square. This should be determined by the players and DM before the trap is sprung.)

Miss: The target rolls a saving throw. If it fails, he is knocked prone, otherwise, he slides himself one square.

Special: One turn later (on the same initiative count) the trap repeats the attack on anyone in the target square, and does half damage and pushes 1 square if it hits.

Wire Mesh

A webwork of thin wires or very strong fibrous vines, covered with sharp bits of metal, thorns, or other slicing tools, is placed between two points, forming a wall. Any creature entering the wall is likely to be injured. The wall can be up to two squares high, and does not need to touch the ground, if there is bracing for it on either side. The wall may be up to 4 squares in size (5 at 14th level, 6 at 19th level), and follows all the usual rules for walls in terms of adjacent squares and layout.

Level: 9,14, or 19 chosen by trapmaker, cannot be higher than trapmaker’s own level.

Check: Moderate Nature or Dungeoneering

Cost: 60 gp per level

Time to create: 25 minutes

Trigger: Entering the target square (targets flyers if they are at the right height).

Attack: Reflex

Hit: 2d10+5 damage and ongoing 5 damage (save ends), +2 points per point of creature’s speed over 6, +1d10 if creature was performing a Run action. In addition, the creature’s movement ends in this square. Increase damage to 2d10+8 at 14th level and to 3d10+8 at 19th level. The wall must make a saving throw; if it succeeds, the wall remains. Otherwise, it collapses.

Miss: The creature’s movement ends in the square it was in just prior to moving into the wall square.

Special: A creature aware of the wall can pass through it very slowly and carefully. It takes four points of movement to move through one square of wall. The wall has AC 14 and 40 hit points (5o at 14th level, 60 at 19th level).

Magical Enhancements

It is possible to channel divine, arcane, or other energies into a trap. This momentarily deprives the character of the use of the power; they regain it as soon as the trap is sprung, or they can recall the energy used as a minor action anytime they are within 5 squares of the trap.

By expending an encounter power of the trap’s level or higher, the following can be added:

Arcane Damage: By empowering the trap with an arcane attack spell which deals damage, the trap will do an additional 1d8 damage of the type used in the spell , plus bonus damage equal to the spell’s level. (So applying a 7th level spell with the fire keyword to a 4th level deadfall trap will cause it do +1d8+7 fire damage).

Divine Guidance: The trap is blessed by the gods. It gains a +2 bonus to all attack rolls, (+4 if the expended power was 11th level or higher), and does the expended prayer’s level in radiant damage in addition to all other effects.

Primal Wisdom: This applies only to traps made with the Nature skill. The primal spirits of the area watch over the trap, and prevent it from triggering against an ally of the trap’s creator. They also confound and misdirect the enemy, so that all Perception checks (including passive perception) to find the traps are at a -2 penalty. (-4 if an 11th level or higher power was expended)


An Addendum

There can and should be some more material here, especially more Paragon (and any Epic) level traps, along with some Thievery-based complex traps to give the rogues more to do. Look for addenda in the future.

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One Response to Traps & Trapmaking

  1. Funnily enough this exact situation came up, like the third session we ever played of 4th edition. We were exploring an area and didn’t want to get attacked from the rear – so we wanted to set up some kind of trap behind us. Our DM made an impromptu skill challenge, which we failed horribly… after that it never really came up again.
    It’s too bad because if there had been a more reliable method (like you present) to make traps I’m sure it would have been an element we would have utilized more.
    Sometimes it’s fun to get one over on the monsters, rather than just trying to avoid one being gotten on you.

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