Bane to and slayer of many an adventurer, traps can be found almost anywhere, but
are most commonly found in diabolically designed dungeons, from clever and conniving
bandit lairs to the tombs of greedy and paranoid long-dead rulers. Just as varied as
the location of traps is the nature of them; they can be a complicated mess of shooting
arrows and swinging blades, or as simple as a 3m deep pit covered in leaves and
thin planks.
Three types of traps exist in I&A, and two (simple and complex) are
described in detail in this chapter. Simple traps are defined by
having at least 1 of 2 characteristics: they are either mechanically simple and can be
constructed relatively easily with materials on-hand, and/or they perform only one
action after being triggered, and must then be reset (either automatically or manually)
before they can do anything else. Complex traps can perform multiple actions
autonomously before they shut down and/or need to be reset.
The third type of traps, which is not covered here, is arcane traps, which are
typically spells that have been set as a trap or a power of an enchanted item.
Detecting Traps
Most every trap has a visible or otherwise detectable component of some sort – a
pressure plate that sticks out, a tripwire that stands apart from the environment,
loose and creaking timbers ready to give way at any moment, etc. If the visible component
of a trap is exceedingly obvious, it can be assumed any nearby creatures see it
immediately without the need for a check – though it is worth noting that just because
a component of a trap is visible doesn’t mean its triggering mechanism is as well,
though it may make spotting the trigger easier.
If a trap’s trigger is not obviously detectable and the players state
that their characters are looking for traps or other dangers, the GM can have them make
Perception checks to look for them (arcane traps may also be detected with a successful
Arcana check). Once a trap or one of its components is spotted, a character can make a
Mechanics/Arcana check to discern how the trap works, its damage, where the trigger is,
etc. The amount and nature of information gained is determined by how well the check
succeeded and the GM’s discretion.
Disabling Traps
Once a trap and/or its trigger has been spotted, it can usually be safely
circumvented by simply avoiding it. Much of the time, however, the safer option – if for
no other reason than peace of mind – may be to disable the trap, either by damaging
it/its trigger and making it utterly useless, or by (temporarily) jamming the
mechanisms of the trap so that it no longer works, but could likely be repaired with
some effort. Thieving Tools will almost always accomplish the desired effect, but they
are not explicitly necessary most of the time, e.g. a normal dagger can cut a tripwire
just fine (usually), or rocks can be stuffed into arrow slits to block them.
The PCs may even be able to trigger a trap from a safe distance, expending it or giving
themselves time until the trap resets to bypass it (this method is especially effective
with arcane traps).
If a character attempting to disarm a trap does not get a
Partial Success, the trap triggers.
Triggering Traps
Each and every trap has a trigger, a specific mechanism that will release the
trap’s effects onto anyone and anything in the area of effect. Three sample
triggers, the Pressure Plate, the Tripwire, and the Opening Door are given here;
the DRs given assume the trigger is uncovered and unmodified in any way. Special
triggers, along with their respective DRs, will be given with their appropriate
traps. Pressure Plate. Spot DR 12, disable DR 10 (STR/DEX). Tripwire. Spot DR 16, no disable DR. Opening Door. Spot DR 16, disable DR 18 (DEX/Thieving Tools).
Avoiding Traps
When a trap is triggered, each creature in the affected area must make a Reflex save to avoid
the trap's effects. On a full success, the saving creature completely avoids the effects of
the trap and they are moved to the nearest space that is outside of the trap's area of effect.
On a Partial Success, the saving creature takes half damage from the trap (if the trap deals
damage over time, this applies only to the first round that the trap deals damage) and has
advantage on the first save against the trap's effects if one is required. On a failure, the
saving creature takes the full effects of the trap. Trap damage is always reduced by a
creature's R-DEF.
Trap Effects
Many traps have many different effects. Though most traps do deal damage and many
are meant to kill, this is not always the case; many are designed to just hinder, maim,
or inconvenience, or a series of traps may be designed to whittle away at a group’s
resources. When designing traps for your adventures and dungeons, consider both the
specific effects of the trap – does it deal damage, restrain a person(s), is it a puzzle
unto itself, etc. – and the overall purpose of the trap – is it designed to whittle
away at intruders, buy time for an enemy to escape, protect a priceless artifact, or
something else entirely? Be creative and have fun with it, but try to ensure that your
traps have a purpose and are not simply a hazard for hazard’s sake.
Sample Traps
Given here are a smattering of example traps designed to be easily understandable,
modifiable, and inspirational, and to give an idea of how to design your own traps. All
the traps given are mechanical in nature, and each trap will specify if it is simple or
complex. The trap’s sample trigger(s) (including spot and disable DRs), area of effect,
effects, and Mechanics DR will all be specified, as well as a couple of possible
modifications for different versions of the trap. Every trap described will be assumed
to be in its most simple, plain, unmodified, and obvious form.
Simple
Area of Effect. May vary, but usually the area immediately around
the alarm.
Effects. The purpose of an alarm is usually to alert the setter of the trap
to any intruders without directly harming the intruders, almost always through loud
and disruptive noise that starts immediately upon the trap being triggered. The
source of the noise can be bells, falling objects, a machine specifically designed
as an alarm, or any other such implement.
Mechanics DR. Pressure plate: 15 – Tripwire: 6.
Sample Modifications
Deafening Alarm.With this variation, the source of the noise is extremely loud
and sudden, and deliberately placed next to the trap trigger. When this version of
the trap is triggered, any creatures within 2 meters of the source of the noise
(usually directly adjacent to the trigger) take 1d6 sonic final damage and must
succeed on a DR 15 Fortitude save
or be deafened for 1 minute. The
Mechanics DR for this version of the trap is 20 (pressure plate)/10 (tripwire), and
any creature that knows how it works has advantage on their save.
Simple
Area of Effect. Any amount of surface area the GM desires.
Effects. When this trap is triggered, the area of effect immediately ignites
and starts burning until the blaze’s fuel runs out, dealing 2d8 burn damage whenever
a creature enters its area of effect and at the start of each affected creature’s
turns.
Mechanics DR. Pressure plate: 20 – Tripwire: 12.
Sample Modifications
Electrified Surface. In this version of the trap, the area of effect becomes
electrified instead of lighting on fire. The Mechanics DR for this version of the
trap is 25 (pressure plate)/22 (tripwire).
Frictionless Surface. This version of the trap may or may not trigger at all;
the surface itself may simply be frictionless by nature, or if there is a trigger,
some sort of liquid or other slickening agent may, for all intents and purposes,
make the surface frictionless. There is no Spot DR for the trigger-less version of
this trap, but the surface itself has a Mechanics DR of 10; for the triggered
version, the Spot DRs are the same, and the Mechanics DRs become 15 (pressure plate)/10
(tripwire).
Simple
Sample Triggers. Explosives: Spot DR 10, disable DR 15
(Explosives Kit) – Loose timbers: Spot DR 6, disable DR 20 (Carpentry
Tools).
Area of Effect. Varies, but usually the same room as the trigger.
Effects. A cave-in trap, as the name would imply, causes a cave-in over the
area of effect, dealing an appropriate amount of physical damage. The amount of
damage this trap deals may vary greatly depending on the materials that are caving
in (natural stone, rotting wood, etc.) and the amount of them (tons of rock and
stone, a few timbers, etc.)
Collapsing Building. If a cave-in would cause more than 1 floor to collapse on
a creature, then for every extra floor, increase the damage the trap deals by a
factor of 1. For example, if a normal wooden roof cave-in would cause 2d6 damage to
its victims, then a 2-story wooden cave-in should deal 4d6, 3 stories would be 6d6,
etc.
Seal-in. This version of this trap is not designed to deal damage, though it
still can. Instead, a seal-in trap is designed to cause a cave-in around 1 or more
of the immediate area’s entrances/exits.
Complex
Sample Triggers. Loose timbers: Spot DR 5, disable DR 20
(Carpentry Tools).
Area of Effect. The area between any length of two or more walls that are
facing each other.
Effects. This trap causes two or more walls that are facing each other to
slide forward towards each other (at a rate of speed determined by the GM), with the
goal of crushing anything between them. If a strong enough object is placed between
them, the closing can be delayed until the pressure destroys the item (or the walls,
depending on their strength). If any creatures in the area of effect do not manage
to leave the area before the walls start to press on them, their Speed will be
halved and they will take 4d12 physical damage (reduced only by their Armor score)
at the start of each of their turns. If a character being crushed is reduced to 0
Health, they are crushed flat and killed instantly.
Spiked Walls. The spiked walls modification is very similar to the original
version, except that spikes sprout from the walls as or before they start closing,
increasing the damage dealt by the crushing walls – or preventing them from closing
entirely, possibly sparing the quick-thinking adventurer.
Rising Floor/Lowering Ceiling. This version of the trap raises the floor to
the ceiling or vice versa, having much the same effect as the standard version,
though it may become more difficult to leave the area of effect.
Complex
Area of Effect. Whatever area(s) the GM chooses.
Effects. This trap causes columns of stone, metal, or other similar material
to slam into the ceiling or floor of the area of effect, causing anything caught in
that area to take damage.
Mechanics DR. Pressure plate: 25 – Tripwire: 25.
Simple
Area of Effect. Any amount of surface area that the GM desires.
Effects. This trap causes spikes to emerge into the area of effect, dealing
1d8 physical damage per spike that occupies the same space as a creature.
Mechanics DR. Pressure plate: 12 – Tripwire: 15.
Sample Modifications
Repeating Spikes. This modification alters the simple nature of the trap, making it complex as
the spikes mechanically and methodically repeat their thrusting motion in and out of
the area of effect. This alteration raises the Mechanics DRs for the trap to 15
(pressure plate)/18 (tripwire), and makes the spikes deal their damage each time
the emerge; so if the spikes emerge every 2 seconds, an affected creature takes damage
from them every 2 seconds.
Surface Blades. This version of the trap causes blades or other similar
cutting implements to eject from the chosen surface.
Simple
Sample Triggers. Timer: Spot DR 10, disable DR 20 (Explosives Kit,
Thieving Tools, or Tinkering Tools).
Area of Effect. Wherever the GM desires.
Effects. When this trap is triggered, the entire area of effect immediately
explodes, causing an appropriate amount of burn damage and knocking everyone caught
in the blast prone. For a guideline on how much damage
this deals, take a look here, under "Explosives Kits".
Shrapnel Blast. With this alteration to the trap, the explosive also blasts
out several small objects into the area of effect, possibly including but not
limited to caltrops, metal shavings, and miniballs, dealing 2d12 additional physical
damage to every affected creature and object.
Simple
Area of Effect. Usually the area immediately around the trigger.
Effects. Similar to the Cave-in trap, this trap simply causes objects (usually
rocks or logs) to fall in the area of effect, dealing damage. The damage dealt
depends on what and how much is dropped.
Swinging Object(s). In this version of the trap, the object(s) that will fall
are attached to a rope, causing them to swing back and forth and possibly causing
creatures caught in the area of effect to take damage again. If the creature does
not notice the object is on a rope, the trap may have advantage on the damage it
deals.
Spiked Object(s). This form of the trap is much like the normal version,
except that the falling object(s) are covered in spikes, dealing 2d8 additional
physical damage.
Burning Object(s). Much like the above modification, this variation simply
means the object(s) is/are on fire, dealing 2d6 additional burn damage.
Simple
Area of Effect. The area immediately in front of the spout,
usually a 2-6 meter line.
Effects. This trap simply sprays a gout of flame into the area of effect,
dealing 2d12 burn damage to anything caught in the blaze.
Repeating Flashes. This modification sees multiple flashes going off in quick
succession, causing effected creatures to remain blinded
until the end of their turn after the flashes stop.
Simple
Area of Effect. A single spot.
Effects. This trap, typically a ring of iron teeth attached to a chain with a
pressure plate in the center, is designed to hinder the victim more than seriously
injure them. When the victim steps on the pressure plate - assuming they fail their
Reflex save - they take 1d6 physical
damage (reduced only by their Armor score) and are grappled
by the trap. While grappled in this
way, they can move only as far as the chain attached to the trap allows, though they
can use 3 seconds to free themselves with a DR 20 STR check; a Partial Success on this
check makes it take 6 seconds, while an outright failure causes them to take 1
final physical damage.
Mechanics DR. Pressure plate: 5.
Sample Modifications
Suspension Snare. This trap, triggered by a tripwire (Spot DR 12,
no disable DR), closes a loop of cord or rope around the ankle(s) of
the victim and then rapidly lifts the loop, suspending the victim
upside-down and making them grappled
by the trap until the cord is cut or the trap is otherwise reset or
destroyed, at which point the victim falls prone.
This version of the trap has a DR 5 Mechanics check.
Simple
Area of Effect. Usually the same room as or area immediately
around the trigger.
Effects. When this trap is triggered, a swarm of insects – hornets, beetles,
spiders, etc. – is released into the immediate area.
Mechanics DR. Pressure plate: 15 – Tripwire: 10.
Sample Modifications
Animal Release. This version of the trap is similar in many respects, except
that instead of insects being released, it is one or more hostile animals.
Simple
Area of Effect. Whatever area the camera is pointed at.
Effects. As soon as the trigger is activated, the camera instantly takes a
picture of whatever it is pointed at.
Mechanics DR. Tripwire: 5.
Sample Modifications
Picture Flash. More useful for dark areas, this version of the trap sees a
flash mounted onto the camera, which goes off at the same time as the picture,
briefly illuminating the pictured area. Any creature not blocking their eyes from
the light is blinded until the end of their next turn.
Simple
Sample Triggers. Weak floor: Spot DR 16, no disable DR.
Area of Effect. Usually the area immediately around the trigger.
Effects. A pit is arguably the simplest trap. Simply put, the
floor of the area of effect collapses, and any creatures caught in that
area can make a DR 15 Reflex save
to avoid falling and taking the appropriate amount of damage when they
land, assuming they fall normally.
Mechanics DR. Pressure plate: 10 – Weak floor: 5.
Sample Modifications
Dangerous Pit. This variation of a pit works mostly the same, the only
difference being that the bottom of the pit has something in it, be it spikes, lava,
a swarm of insects, or anything else that adds danger to the pit. If the danger is
not liquid, the falling creature takes falling damage as normal + whatever damage
the added danger deals. If it is liquid, the falling creature takes half falling
damage + whatever damage the liquid deals, if any.
Complex
Area of Effect. Usually the same room as the trigger.
Effects. This trap, usually accompanied by the entrances/exits to
the room being sealed, causes a
poisonous gas of some sort to
start filling the area of effect. For each round that this trap is
active after the first three, the victims must succeed on the
Fortitude save for the poison at
the start of each of their turns until they leave the area of effect.
Mechanics DR. Pressure plate: 15 – Tripwire: 15.
Simple
Area of Effect. (A) straight line(s).
Effects. An absolute classic, this trap causes a projectile of
the GM’s choice to fly towards the victim(s) after being fired from an
appropriate mechanism, be it a jerry-rigged crossbow or something more
complex that fires a multitude of projectiles over a larger area. For
each projectile being fired, assume the damage each one deals is equal
to 2 proficiency with the appropriate weapon, e.g. 3 light crossbow
bolts being fired would deal 6d6 physical damage.
Flaming Projectiles. This modification of the trap is very similar to the
base form, except that the projectiles in question are now on fire, dealing 1d4
additional burn damage per projectile (this does not work with bullets or miniballs).
Complex
Area of Effect. A room of the GM’s choosing, usually the same one
as the trigger.
Effects. This trap simply causes water in the room to start rising at a rate
that is up to the GM as the entrances/exits to the room seal shut.
Mechanics DR. Pressure plate: 25 - Tripwire: 25.
Sample Modifications
Rising Danger. This version of the trap replaces the water with
some sort of immediately dangerous fluid, such as acid or lava. Assume
the danger deals 1d8 of the appropriate damage on the first round and
an additional d8 every round after that. This damage is taken by every affected
creature at the
start of the round and is reduced only by their Armor score if
their armor is specifically enchanted against the danger; otherwise, the
damage is considered final.
Simple
Area of Effect. A straight line on a downhill slope of the GM’s
choice.
Effects. The bane of archaeologists the world over, a rolling
boulder or log can pancake any amateur adventurer, and still presents a
serious threat to experienced ones. An example amount of damage would
be 5d10 physical.
Mechanics DR. Pressure plate: 15 - Tripwire: 15.
Sample Modifications
Burning Boulder/Log. Lighting a rapidly-rolling object on fire
will cause it to deal 2d6 additional burn damage.
Spiked Boulder/Log. This variation adds spikes onto the rolling
object, causing it to deal 2d8 additional physical damage.
Simple
Area of Effect. An amount of space that the GM chooses.
Effects. This trap causes a prison to spring into existence, be it gates
slamming down, a cage falling into place, or something else entirely. When a
creature triggers this trap, they can make a DR 24 Reflex
save to avoid being imprisoned.
Area of Effect. The area immediately under the bucket, usually
the same area as trigger.
Effects. When this trap is triggered, any creature(s) caught in the area of
effect immediately have the contents of the bucket are dumped on them, be it acid,
spiders, flammable oil, or something else entirely.
Mechanics DR. Opening door: 10 – Tripwire: 5.
Simple
Area of Effect. The area immediately adjacent to the trigger.
Effects. When this trap is triggered, a weapon swings out
(usually down) and strikes the victim, dealing damage equal to 3
proficiency with the weapon.
Swinging Blades. This alteration makes the trap complex, as a multitude
of blades or other weapons swing across an area of the GM’s choice repeatedly. This
raises all of the Mechanics DRs by 10.
