Combat as a Complex Trap

I often find that for cinematic combat scenes, the mechanics of D&D don’t quite achieve exactly what I need them to. Specifically, I don’t think 5th Edition is great at handling hordes of creatures – like a chamber filled with skeletons – or creatures of immense proportion and epic challenge – like a kraken that eats ships for breakfast, or any creature with the Siege Monster feature.

One way I’ve been thinking of changing things up in this regard is to use the mechanics laid out in the Complex Traps section of chapter 2, page 118, of Xanathar’s Guide to Everything. Here they define 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. 

Does this sound so far away from a cinematic combat encounter like we described? A monster or group thereof that poses multiple dangers to adventurers that remains dangerous round after round until avoided or disabled. Some become more dangerous over time. All require a series of checks, or perhaps attacks, to destroy. I think it’s pretty similar, and I’m going to give some guidelines here about how to run combat as a complex trap.

If you think this is awful, reply with some hate mail or call me out on Twitter!

Combat Trap Anatomy

Each complex trap is made up of certain codified elements defined in XGtE. Here I’m going to break those elements down, talk about how they can be repurposed for what I’m calling a ‘combat trap’, and give examples as I go. I’ll also give some full examples at the end of the email.

Level and Threat

We all know that challenge rating is broken. It just doesn’t accurately represent the challenge of a monster. However, in XGtE there’s a great set of tables that show us how to alter the damage, DC, and spell level of traps based on the level of character the trap is designed for, and the threat level of the trap. These tables aren’t infallible, but they’ll give a good idea of what numbers to use for your combat traps.

Example. Let’s say you want a skeletal swarm that should be a deadly threat for your 6th level characters. By following the table guidelines, we can see that their abilities should have a save DC of 20, their attacks should have a +12 to hit, they should deal 55 (10d10) points of damage to one character or 35 (10d6) damage to multiple characters (the swap of a d10 for a d6 is explained in the paragraph above the tables, which can be found on page 116). If we wanted the skeletal swarm to have spellcasting abilities (or at least abilities that might have the same effects as spells, such as fear) the table tells us that 6th level spells would be deadly.

NB. These tables work out pretty well, if we assume that the trap does, indeed, do 35 points of damage a round to the 6th level characters, they’ll be dead in two rounds (assuming they have average hit points, are hit by all effects, and do nothing to stop it).


This is probably the least important element of our combat traps, but it can make it more interesting. It’s always useful to consider ways that characters encounter monsters beyond just walking into their bedroom and finding them standing in the centre of the chamber staring deadpan at the door.

Example. Perhaps the kraken is only summoned from the depths if a ship is sailed out past the beacons, and the skeletal swarm animates from a pile of bones when a cursed treasure is picked up.


If you’re rolling initiative for your monsters you’re insane. Just take 10 + Dex and spend the time you saved arranging the initiative cards of the characters. XGtE suggests that complex traps that are slow should act on initiative count 10, fast on 20, and very fast on both 20 and 10. For our combat trap, consider how many different attacks the monster can make rather than its speed. If the monster can make one attack per round set it as ‘slow’, 2 or 3 as ‘fast’, and 4 or more as ‘very fast’. When determining the number of attacks per round, discount ‘repeat’ attacks i.e. a duplicate of the same attack from the same source, like two bites from multiattack. If you want to customise this a little more, feel free to add the initiative bonus of the monster to these static scores.

Example. Skeletons in the Monster Manual don’t have multiattack or any other way to get attacks save opportunity attacks, which I’m ignoring. Thus, I set their initiative as ‘slow’ – they act on 10. I feel like making them slightly harder on the characters though, so I boost it to 12 by adding their Dexterity modifier. A kraken can make four different kinds of attacks – tentacles as part of multiattack, fling as part of multiattack, tentacle as legendary action, and lightning storm as legendary action. I set its speed as ‘very fast’ – acting on 20 and 10.

Active Elements

These are basically the combat trap’s attacks. You just had a look at them while determining initiative, so you have an idea of the flavour, but the actual numbers should come from the table in the ‘Level and Threat’ section. That table tells what the save DC, attack bonus, and damage should be. You just need to decide what’s most relevant for your monster.

Example. Skeletons have shortsword or shortbow attacks. In my imagination, I see them clawing at the characters, so I’m going to ignore the bows and swap to slashing damage for raking claws, rather than piercing from swords. Thus, I create the ‘Raking Claws’ active element which occurs on initiative 10, has a +12 bonus to the roll, and deals 10 (3d6) slashing damage on a hit (the other 7d6 damage is coming later on).

For the kraken this process is much more involved – they should definitely have a tentacle attack in there, also a fling or something similar, plus an active element similar to a lightning storm. Always put the fiction first – think about what the kraken is doing and then make your elements.

Dynamic Elements

These represent threats that arise or evolve while the combat trap is in play. Basically things that get better or worse over time or because of the characters’ actions. If your combat trap gets deadlier over time or as the characters ‘disarm’ it, then consider starting your damage slightly lower (say two dice of damage) than the table suggests. Similarly, if the damage lessens over time or through countermeasures, start the damage of your active elements two dice of damage higher.

Example. I like the idea that over time, more and more skeletons begin to animate and join the swarm. Thus, I say that the combat trap has the dynamic element ‘Growing Swarm’ which says that the damage from the Raking Claws element increases by 7 (2d6) each round after it activates, to a maximum of 56 (16d6). I got this maximum from the table too – the amount of damage that should be dealt to one character by a trap of this level and threat. It’s a good benchmark, and it’ll probably never rise that high anyway. For the kraken, it makes sense to keep tentacle and fling-like attacks static in damage, but maybe the gathering lightning storm increases in damage over time.

Constant Elements

Constant elements pose a threat to characters even when it’s not the combat trap’s turn. They typically make attack rolls or force saving throws. These could be things like damage-dealing auras, riotous swarms of flailing limbs, environmental effects drawn from lair actions, or similar effects. They typically affect creatures that end their turn in a certain area. Feel free to be as specific or vague as you like – within the kraken’s reach is just as good as within 30 feet of the kraken, given that these are cinematic scenes rather than strictly gridded combat.

Example. As it’s a massive, growing swarm, I figure that the pile of skeletons might surround the characters. They need to dodge the flailing limbs of these undead, which is no mean feat. I come up with the Flailing Limbs constant element; creatures that end their turn in the swarm’s area (being intentionally vague here) must succeed on a DC 20 Dexterity saving throw, taking 17 (5d6) bludgeoning damage on a failed save, or half as much on a successful one.


These combat traps are not just bags of hit points like a normal combat encounter. They’re cinematic scenes where certain conditions must be met to win, which goes beyond just pummeling the kraken to deal with a mace. Consider this text from XGtE:

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.

Try to think about which elements of your combat trap could be ‘disabled’ or defeated. What sort of spells and checks would achieve this? If attack rolls make sense i.e. the creatures in the combat trap can be stabbed to death, then include them! For an AC, rip the DC from the tables at the top, or use the actual AC of the creature. If you want, a successful hit could count as a ‘successful check’ to disarm the trap. To make it harder, consider having a damage threshold – only attacks that deal 10 damage or more count as successful, for example. If you’re using damage thresholds, I’d suggest 10 damage from a single attack for a moderate threat, 20 damage for a dangerous threat, and 50 for a deadly threat. Of course, vary this as makes sense to the narrative. Maybe your kraken is so colossal that stabbing it with a pike just doesn’t bother it at all, or perhaps it’s a sinewy creature that is easily chopped up.

Remember that countermeasures can be used to detect the trap in the first place, to disable some element of the trap once it’s been activated, or to mitigate the damage of the trap once activated. Take a look at the Path of Blades trap on page 118 for examples. Some elements can be dodged, some damaged, some are impervious, and there are a few specific ways to actually disable the trap.

Example. My skeletal swarm was triggered by a cursed treasure item, so I decide that removing the curse on that item is the only way to stop the swarm for good. The curse can be removed with three successful DC 20 Intelligence (Arcana) checks, each of which requires an action. Once a creature attempts a check for this purpose, no other character can do so until the end of that creature’s next turn. Alternatively, the curse can be disabled with three successful castings of remove curse targeting the treasure. I also decide to add in some ways that the damage of the skeletons can be lessened, such as by deliberately dodging them or by attacking them to reduce their numbers.

When to use Combat Traps

I mentioned it at the top, but it bears repeating. I would not use these combat traps all the time. Probably not even once per session. I think they’re a great way of handling combat with either massive swarms of creatures, or for enormous creatures of epic proportions that won’t mind a spear sticking out their side. I’d only use them if at least one of the following conditions is true:

  • The characters are fighting a swarm
  • The characters are fighting a creature impervious to normal damage, or that would not be bothered by all but the mightiest attacks
  • The characters don’t want to kill the creature, but do want to ‘disable’ it in some way (through diplomacy, for example)
  • You want to adjust an existing monster to make it a balanced challenge for characters of a different level

As well as the examples provided below, I like the idea of an enraged gang of goblins that attacks until they’re all killed (through dealing damage to them), they’re convinced the characters mean no harm (through successful Charisma (Persuasion) checks), or they’re scared off by the characters (through successful Charisma (Intimidation) checks). You could also reskin the complex traps in XGtE to be monsters – maybe the Path of Blades is a group of golems, one of which is engraved with a fear rune. Maybe the Sphere of Crushing Doom is a rolling galeb duhr which circles around rather than going through a portal. Perhaps the Poisoned Tempest is a gorgon exhaling noxious fumes.

Example Combat Traps

Skeletal Swarm

Combat trap (level 5-10, deadly threat)

Hidden in the vault of the lich Therax the Indomitable is a cursed treasure; a gilded skull etched with eldritch patterns and set with gemstones. The skull sits pride of place in a trophy room, surrounded by bones of deceased adventurers.
Trigger. This trap activates as soon as a non-undead creature touches the treasure, and remains active until non-undead creatures leave the trophy room or are killed.
Initiative. The trap acts on initiative count 20 and initiative count 10.
Active Elements. The Skeletal Swarm is animated, then uses its limbs to reach out and attack creatures in its area in a coordinated strike.
Swarm Animates (Initiative 20). A dozen or so skeletons animate from the piles of bones on the floor and come together as a swarm. This effect activates only once the first time the trap is triggered.

Raking Claws (Initiative 10). The skeletal swarm attacks each creature in its area, with a +12 bonus to the attack roll and dealing 10 (3d6) slashing damage on a hit.

Dynamic Elements. The skeletal swarm grows in number the longer the trap remains active, making it deadlier.

Growing Swarm. The damage from the Raking Claws element increases by 7 (2d6) each round after it activates, to a maximum of 56 (16d6).

Constant Elements. The skeletal swarm affects each creature that ends its turn in its area.

Flailing Limbs. Any creature that ends its turn in the swarm’s area must make a DC 20 Dexterity saving throw, taking 17 (5d6) bludgeoning damage on a failed save, or half as much on a successful one.

Countermeasures. The trap can only be overcome by removing the curse from the skull. The skeletal swarm can be thwarted by particular countermeasures.

Raking Claws & Failing Limbs. Characters can smash the skeletons to pieces, actively dodge their attacks, or use holy magic to neutralise them.

Damage. A creature can try to deal damage to the swarm. The creature has disadvantage on their next saving throw against the Flailing Limbs element. The swarm has AC 13, and the same saving throw bonuses as a skeleton. Dealing 20 or more damage to the swarm reduces the damage of the Raking Claws and Flailing Limbs elements by 7 (2d6), as does a failed saving throw against incapacitating spells such as hypnotic pattern.

Dodge. A creature that takes the Dodge action imposes disadvantage on the next Raking Claws attack against them, and has advantage on their next dexterity saving throw against the Flailing Limbs.

Holy Magic. Creatures can use Turn Undead, splash holy water, or use similar holy magic to disrupt the skeletal swarm. Use of any of these methods automatically succeeds, and reduces the damage of the Raking Claws and Flailing Limbs elements by 7 (2d6).

Remove the Curse. The curse can be removed from the skull with three successful DC 20 Intelligence (Arcana) checks, each of which requires an action. Once a creature attempts a check for this purpose, no other character can do so until the end of that creature’s next turn. Alternatively, the curse can be disabled with three successful castings of remove curse targeting the treasure.

The Kraken

Combat trap (level 6-11, dangerous threat)

A kraken lurks out there in the deep. It has its territory, marked by the beacons. Cross them and you’ll truly learn of the ocean’s wrath.

Trigger. This trap activates as soon as a ship crosses the beacons, and remains active until the ship crosses back or is destroyed.
Initiative. The trap acts on initiative count 20 and initiative count 10.
Active Elements. The kraken makes a tentacle attack against a ship within 30 feet of it, flings an object such as a barrel or anchor at a creature, and summons a lightning storm.

Tentacles (Initiative 20). The kraken slams its tentacles onto a ship within 30 feet of it with a +8 bonus to the attack roll and dealing 55 (10d10) bludgeoning damage on a hit. Each creature standing on the deck must succeed on a DC 15 Strength saving throw or fall prone and take 10 (3d6) bludgeoning damage.

Fling (Initiative 20). The kraken flings an object against a creature within 60 feet of it with a +8 bonus to the attack roll and dealing 55 (10d10) bludgeoning damage on a hit.

Lightning Storm (Initiative 10). A lightning bolt shoots from storm clouds above at each creature within 120 feet of the kraken, each of whom must make a DC 15 Dexterity saving throw, taking 17 (5d6) lightning damage on a failed save or half as much on a successful one.

Dynamic Elements. The lightning storm becomes more dangerous the longer the kraken sustains its attack. Furthermore, the kraken can eject ink in a cloud beneath the water to protect itself against attack.

Storm Clouds Gather. The damage from the Lightning Storm element increases by 7 (2d6) each round after it activates, to a maximum of 38 (11d6).

Ink Cloud. Each successful attempt to damage the kraken causes it to emit a cloud of ink in the water around it in a 60-foot radius. This area is heavily obscured to creatures other than the kraken. A strong current disperses the cloud, which otherwise disappears at the end of the next initiative count 10.

Constant Elements. The kraken continues to lash out with its tentacles at ships that end their turns within 30 feet of it.

Whirlwind of Tentacles. Any ship that ends its turn within 30 feet of the kraken is targeted by a tentacle attack: +8 attack bonus; 35 (10d6) bludgeoning damage on a hit.

 Countermeasures. There are a few ways that the kraken can be overcome.

Kill the Kraken. Killing the kraken is the hardest way to disable the trap. To kill the beast, the characters must first destroy its tentacles, then destroy its brain. The kraken’s tentacles have AC 15. Attacks or spells that deal 50 or more damage in a single hit reduce the damage dealt by the Tentacles effect by 11 (2d10). Once this reaches 0, the kraken’s Tentacles, Fling, and Whirlwind of Tentacles elements are disabled. The characters can then attack the kraken’s head, which has AC 18. The third attack that deals 50 damage or more to the head in a single hit kills the kraken, and disables the trap.

Outsail the Kraken. Expert sailors can try to navigate around the kraken and escape it’s wrath. They could head out beyond it, or back to the safety of the beacons. To outsail the kraken, a character must first succeed on a DC 15 Wisdom (Navigation) check to set a reasonable course. A successful DC 15 Strength (Athletics) check is then required to adjust course using the ship’s wheel. Success on a DC 15 Intelligence (Sleight of Hand) check allows the sails to be adjusted. Finally, a successful DC 15 Charisma (Deception) or Wisdom (Animal Handling) check is needed to distract the kraken for long enough to escape. Each check requires an action.

Beg for Mercy. A creature can beg the kraken for mercy with three successful DC 15 Charisma (Religion) checks. Each check requires an action. A creature must be within 30 feet of the kraken to attempt the check, and only one creature can work on this task at once. Once a creature attempts a check for this purpose, no other character can do so until the end of that creature’s turn. Successfully begging for mercy allows a ship to return to the safety of the beacons without further damage.

Published by JVC Parry

Welcome all! My name is Josh and I publish and create RPG content as JVC Parry. The vast majority of what I write about will be related to Dungeons & Dragons 5th edition, but I also dabble in some system neutral stuff and board games too! You can find me in these places: Twitter: Facebook: DMsGuild:

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