Complex Traps

A complex trap poses multiple dangers to adventurers. After a complex trap activates, it remains dangerous round after round until the characters avoid it or disable it. Some complex traps become more dangerous over time, as they accumulate power or gain speed.
Complex traps are also more difficult to disable than simple ones. A single check is not enough. Instead, a series of checks is required to slowly disengage the trap's components. The trap's effect degrades with each successful check until the characters finally deactivate it.
Most complex traps are designed so that they can be disarmed only by someone who is exposed to the trap's effect. For example, the mechanism that controls a hallway filled with scything blades is on the opposite end from the entrance, or a statue that bathes an area in necrotic energy can be disabled only by someone standing in the affected area.

Describing a Complex Trap

A complex trap has all the elements of a simple trap, plus special characteristics that make the trap a more dynamic threat.
Level and Threat. A complex trap uses the same level and severity designations that a simple trap does.
Trigger. Just like a simple trap, a complex trap has a trigger. Some complex traps have multiple triggers.
Initiative. A complex trap takes turns as a creature does, because it functions over a period of time. This part of a trap's description tells whether the trap is slow (acts on initiative count 10), fast (acts on initiative count 20), or very fast (acts on initiative count 20 and also initiative count 10). A trap always acts after creatures that have the same initiative count.
Active Elements. On a trap's turn, it produces specific effects that are detailed in this part of its description. The trap might have multiple active elements, a table you roll on to determine its effect at random, or options for you to choose from.
Dynamic Elements. A dynamic element is a threat that arises or evolves while the trap functions. Usually, changes involving dramatic elements take effect at the end of each of the trap's turns or in response to the characters' actions.
Constant Elements. A complex trap poses a threat even when it is not taking its turn. The constant elements describe how these parts of the trap function. Most make an attack or force a saving throw against any creature that ends its turn within a certain area.
Countermeasures. A trap can be defeated in a variety of ways. A trap's description details the checks or spells that can detect or disable it. It also specifies what happens, if anything, on a failed attempt to disable it.
Disabling a complex trap is like disarming a simple trap, except that a complex trap requires more checks. It typically takes three successful checks to disable one of a complex trap's elements. Many of these traps have multiple elements, requiring a lot of work to shut down every part of the trap. Usually, a successful check reduces a trap element's effectiveness even if it doesn't disable the trap.

Running a Complex Trap

A complex trap functions in play much like a legendary monster. When it is activated, the trap's active elements act according to its initiative. On each of its initiative counts, after all creatures with that same initiative count have acted, the trap's features activate. Apply the effects detailed in the trap's description.
After resolving the effects of the trap's active elements, check its dynamic elements to see if anything changes about the trap. Many complex traps have effects that vary during an encounter. A magical aura might do more damage the longer it is active, or a swinging blade might change which area of a chamber it attacks.
The trap's constant elements allow it to have effects when it isn't the trap's turn. At the end of each creature's turn, look at the trap's constant elements to see if any of their effects are triggered.

Experience for Complex Traps

Overcoming a complex trap merits an experience point award, depending on the danger it poses. Judging whether a party has overcome a trap requires some amount of adjudication. As a rule of thumb, if the characters disable a complex trap or are exposed to its effects and survive, award them experience points for the effort according to the table below.

Complex Trap Experience Awards

Trap Level	Experience Points
1-4	650
5-10	3,850
11-16	11,100
17-20	21,500

Designing Complex Traps

Creating a complex trap takes more work than building a simple one, but with some practice, you can learn the process and make it move quickly.
Familiarize yourself with the advice on designing a simple trap before proceeding with the guidelines on complex traps.

Purpose

Complex traps are typically designed to protect an area by killing or disabling intruders. It is worth your time to consider who made the trap, the trap's purpose, and its desired result. Does the trap protect a treasure? Does it target only certain kinds of intruders?

Level and Lethality

Complex traps use the same level designations and lethality descriptors that simple traps do. Refer to that section for a discussion of how level and lethality help determine saving throw and check DCs, attack bonuses, and other numerical elements of a complex trap.

Map

A complex trap has multiple parts, typically relies on the characters' positions to resolve some of its effects, and can bring several effects to bear in each round. The traps are called complex for a reason! To begin the design process, consider drawing a map of the area to be affected by the trap on graph paper, using a scale of 5 feet per square. This level of detail allows you to develop a clear idea of what the trap can do and how each of its parts interact. Your map is the starting point and context for the rest of the design process.
Don't limit yourself to one room. Look at the passages and rooms around the area of the trap and think about the role they can play. The trap might cause doors to lock and barriers to fall into place to prevent escape. It could cause darts to fire from the walls in one area, forcing characters to enter rooms where other devices trigger and threaten them.
Consider how terrain and furniture can add to the trap's danger. A chasm or a pit might create a buffer that allows a trap to send bolts of magic at the characters, while making it difficult or even impossible for them to reach the runes they must deface to foil that attack.
Think of your map like a script. Where do the characters want to go? What does the trap protect? How can the characters get there? What are their likely escape routes? Answering these questions tells you where the trap's various elements should be placed.

Active Elements

A complex trap's active elements work the same way as a simple trap's effects, except that a complex trap activates in every round. Otherwise, the guidelines for picking saving throw DCs, attack bonuses, and damage are the same. To make your trap logically consistent, make sure the elements you design can activate each round. For instance, ordinary crossbows rigged to fire at the characters would need a mechanism for reloading them between attacks.
In terms of lethality, it's better to have multiple dangerous effects in a trap than a single deadly one. For example, the Path of Blades trap uses two dangerous elements and one moderate element.
It's useful to create multiple active elements, with each affecting a different area. It's also a good idea to use a variety of effects. Some parts of the trap might deal damage, and others might immobilize characters or isolate them from the rest of the party. A bashing lever might knock characters into an area engulfed by jets of flame. Think about how the elements can work together.

Constant Elements

In addition to the active steps a complex trap takes, it should also present a continual hazard. Often, the active and constant effects are the same thing. Imagine a hallway filled with whirling saw blades. On the trap's turn, the blades attack anyone in the hall. In addition, anyone who lingers in the hallway takes damage at the end of each of their turns, accounting for the constant threat that the blades pose.
A constant element should apply its effect to any creature that ends its turn in that element's area. If an active element presents a threat when it isn't the trap's turn, define the threat it poses as a constant element. As a rule of thumb, keep the saving throw DC or attack bonus the same as for the active element but reduce the damage by half.
Avoid filling the entire encounter area with constant elements. Part of the challenge of a complex trap lies in figuring out which areas are safe. A moment's respite can help add an element of pacing to an encounter with a complex trap and give the characters the feeling that they aren't in constant peril. For example, walls that slam together might need to reset between slams, making them harmless when it isn't their turn to act.

Dynamic Elements

Just as a battle is more interesting if the monsters change their tactics or unveil new abilities in later rounds, so too are complex traps more fun if their nature changes in some way. The whirling blades that protect a treasure chest do more damage each round as they speed up. The poison gas in a room grows thicker as more of it floods the chamber, dealing greater damage and affecting line of sight. The necrotic aura around an idol of Demogorgon produces random effects each time its active element is triggered. As water floods a chamber, the characters must swim across areas they could walk through just a round or two earlier.
Since a complex trap remains active over the course of several rounds, it might be possible to predict its future behavior by examining how it functions. This information can give its targets a much better chance of thwarting it. To minimize this possibility, design your trap so that it presents multiple threats that can change each round. The changes can include how a trap targets creatures (different attacks or saving throws), the damage or effects it produces, the areas it covers, and so on. Some traps might have a random effect each round, while others follow a carefully programmed sequence of attacks.
Dynamic elements usually occur according to a schedule.
For a room that floods, you can plan out how the rising water level affects the area each round. The water might be ankle deep at the end of the first round, knee deep the next, and so on. Not only does the water bring a risk of drowning, it also makes it harder to move across the area. On the other hand, the rising water level might allow characters to swim to the upper reaches of the chamber that they couldn't get to from the floor.
Dynamic elements can also come into play in reaction to the characters' actions. Disarming one element of the trap might make the others deadlier. Disabling a rune that triggers a fire-breathing statue might cause the statue to explode.

Triggers

The advice on triggers given for simple traps also applies to complex traps, with one exception. Complex traps have multiple triggers, or are designed such that avoiding a trigger prevents intruders from reaching the area the trap guards. Other complex traps use magical triggers that activate on specific cues, such as when a door opens or someone enters an area without wearing the correct badge, amulet, or robe.
Look at your map and consider when you want the trap to spring into action. It's best to have a complex trap trigger after the characters have committed to exploring an area. A simple trap might activate when the characters open a door. A complex trap that triggers so early leaves the characters still outside the trapped room, in a place where they could decide to close the door and move on. A simple trap aims to keep intruders out. A complex trap wants to lure them in, so that when it activates, the intruders must deal with the trap before they can escape.
The trigger for a complex trap should be as foolproof as you can make it. A complex trap represents a serious expenditure of effort and magical power. No one builds such a trap and makes it easy to avoid. Wisdom (Perception) and Intelligence (Investigation) checks might be unable to spot a trigger, especially a magical one, but they can still give hints about the trap before it triggers. Bloodstains, ashes, gouges in the floor, and other clues of that sort can serve as evidence of the trap's presence.

Initiative

A complex trap acts repeatedly, but unlike characters and monsters, traps don't roll for initiative. As mechanical or magical devices, their active elements operate in a periodic manner. When designing a complex trap, you need to decide when and how often its active elements produce their effects.
In a trap with multiple active elements that work in concert, those different elements would act on different initiative counts. For instance, on initiative count 20, blades sweep across a treasure vault, driving the characters back into the hallway. On initiative count 10, magic darts fire from statues in the hallway while a portcullis falls to confine the characters.
Initiative 10. If a trap's active element takes time to build up its effects, then it acts on initiative count 10. This option is good for a trap that functions alongside allied monsters or other guardians; the delay before it acts can give guards the chance to move out of its area or force characters into the area before the trap triggers.
Initiative 20. If an element is designed to surprise intruders and hit them before they can react, then it acts on initiative count 20. This option is generally best for a complex trap. Think of it as the default. Such a trap acts quickly enough to take advantage of most characters, with nimble characters like rogues, rangers, and monks having the best chance to move out of the area before the element activates.
Initiative 20 and 10. Some active elements are incredibly fast acting, laying waste to intruders in a few moments unless countered. They act on initiative count 20 and 10.

Defeating Complex Traps

A complex trap is never defeated with a single check. Instead, each successful check foils some part of it or degrades its performance. Each element of the trap must be overcome individually to defeat the trap as a whole.
As part of determining how your trap can be overcome, look at your map and consider where the characters must be located to attempt an action that can foil part of the trap. As a rule, the characters should need to be near or adjacent to an element to have a chance of affecting it. An element can be designed so that it protects itself. A fighter might be able to break a whirling blade, but moving close enough to attack it requires giving the blade a chance to strike.
What methods are effective against your trap? Obvious candidates are activities covered by the same sorts of checks used to defeat simple traps, but use your knowledge of the trap's design to identify other options. A valve that leaks poison gas into a room can be stopped up. A statue that emits a deadly aura can be pushed over and smashed. Attacks, spells, and special abilities can all play a role in undermining a trap.
Leave room for improvisation by the characters. Don't create a few predetermined solutions and wait for the players to figure out the right approach. If you understand the mechanism behind how a trap works, that makes it much easier for you to respond to the players' ideas. If a character wants to try something you haven't allowed for, pick an ability, assess the chance of success, and ask for a roll.
Shutting down one part of a complex trap usually requires multiple successes. As a default, it takes three successful checks or actions to disable an element. The first successful check might reduce the element's saving throw DC or attack bonus. The second successful check might halve the element's damage, and the final successful check shuts it down.
For elements that don't attack, allow each successful check to reduce that element's effectiveness by one-third. A lock's DC is decreased, or a gate opens wide enough to allow a Small character to squeeze through it. A mechanism pumping poison gas into the room becomes defective, causing the gas's damage to increase more slowly or not at all.
It takes time to disable a complex trap. Three characters can't make checks in rapid succession to disarm a complex trap in a matter of seconds. Each would get in another character's way and disrupt the effort. Once a character succeeds on a check, another character can't attempt the same check against the same trap element until the end of the successful character's next turn.
Not all of the characters' options need to be focused on stopping a trap from operating. Think of what characters can do to mitigate or avoid a trap's effects. Making the trap vulnerable to this sort of effort is a way to engage characters who might be ill-suited to confront the trap directly. A successful Intelligence (Religion) check might provide insight into the imagery displayed by a trap in a temple or shrine, giving other characters a clue about how and where to direct their efforts. A character could stand in front of a dart trap while holding a shield that the darts can target harmlessly, while other characters trigger that element as they work to disable it.