Unearthed Arcana: Traps Revisited Analysis

This week the D&D team provides extra rules for designing traps.


The traps in the Dungeon Master’s Guide are separated into mechanical and magical. This document separates traps into two other categories: simple and  complex. The document’s focus is to provide insight on how to design traps, but it also contains a few of them as example.


Simple Traps

Simple traps are the ones that activate once, do what they’re supposed to do, and then become harmless.

There are four elements you have to consider when creating a simple trap. The first three are the Trigger, the Effect, and the Countermeasure which are all pretty much self explanatory. Also, a simple trap has a level and a threat label, which can be moderate, dangerous, or deadly.

Then we get a few paragraphs on how to run simple traps which contains some simple (heh) advice. The most important advice, in my opinion, is to have the players be very specific when trying to disarm a trap. However, the problem with that is that the document doesn’t provide enough information on how to make the players do that.

Designing simple traps is a straightforward process. First, you have to decide its purpose. A trap can alarmdelayrestrain, slay, or of course do a combination of those. Then you get to figure out the level and lethality of them. There are three tables that can help you decide DCs, attack modifiers, as well as damage and spell levels. After that, you need to think about how it’s going to get triggered. Triggers can be various things but all of them have one thing common and that is they must be hidden in some way. Then you reach the best part, coming up with all the fun effects you’re going to load your trap with. Think about what you want it to do and then consult the tables provided. Finally, just to be fair, you have to design a way your players can disarm it. Disarming a simple trap just needs an ability check which usually is a Dexterity check to use the thieves’ tools, an Athletics check, or an Arcana check. There are two important notes to keep from this, in my opinion. Traps can be just bypassed (for example the pit trap is bypassed by just using the ledge) and also trying to disarm one doesn’t always ends up well. Also, my advice is that you should come up with various wild ways someone can disarm a trap and not to just stick to the usual three checks. For example, the activation panel could be a small puzzle and solving it deactivates the trap.

Placing the trap correctly is also extremely important. You don’t want your precious little pit trap be completely avoided because it was placed in a huge corridor and the characters chose to walk around it. Also, an alarming trap will probably do poorly if you place it in the room where the final battle of a dungeon takes place. I mean, the BBEG already knows you’re there because they’re looking at you!

Finally, I’d like to go over the nine simple traps we get as examples.

  • Bear Trap. Nothing special here. It does an okay amount of damage, but the most important thing about this trap is that it restricts movement. Also, note that the attack the trap does when is triggered cannot be made with advantage or disadvantage. So, for example, there is no disadvantage on the attack when an invisible creature steps on it but also there is no advantage if a paralyzed creature is put onto the trap.
  • Crossbow Trap. I like crossbow traps. The can make two attacks but not necessarily on the same target.
  • Falling Gate. This trap isn’t dangerous by itself but can help the DM create some difficult situations for the characters. A good idea is to combine it with other traps.
  • Fiery Blast. I really like the very specific detail that can protect you from triggering the trap. Of course, Pyremius can be swapped with anything, as well as the damage type. My only question is what happens if someone tries to deface the whole mosaic and not only the key rune? I guess that’s for the DM to decide.
  • Net Trap. This is a kinda smart trap. If the trap is triggered, the enemies are warned even if the net doesn’t restrain anyone. If it does, then the enemies get more time to prepare for the incoming threat.
  • Pit Trap. Dig a hole, cover it with something that breaks easily, and wait for something to fall inside. The Dungeon Master’s Guide provides a few variations of this trap, since it’s quite easy to modify one. For example, you can remove the ledges from the sides of the pit which can make
  • Poison Needle. This is a bit different from the DMG poison needle. You roll one saving throw for taking the damage and becoming poisoned. Also the damage is slightly more and the time you’re poisoned is now 10 minutes. Detecting it is pretty much the same, but disarming it is harder now.
  • Scything Blade. Another classic trap. With some modifications it could be turned into a skill challenge.
  • Sleep of Ages. This is indeed a deadly threat. While it can’t kill anyone by itself, a 9th level Sleep spell could easily change the result of a battle.


Complex Traps

Now let’s go to something a bit more intricate. Complex traps are deadlier, more difficult to disarm or avoid, and even more fun. They build on the template of the simple traps, which is something I like because it removes possible unnecessary complexity.

Complex traps should be ran pretty much like legendary monsters. They are comprised of various parts which, when activated, have their own initiative and may even act twice per round. There are also parts that pose a constant threat without an initiative and parts that change as time goes by.

When designing complex traps, the first difference between them and simple ones is that the first can, and should, take up more space than just a room. That’s why having a map of the area affected by the trap might prove helpful.

You can view an active element of a complex trap like a simple trap by itself but with the difference it activates each turn after it has been triggered. Also, having a bunch of less dangerous elements is better than having only a really dangerous one. That actually makes sense, especially since you want to make a wider area dangerous than just a room. Moreover, mixing and matching effects is a good strategy. Avoiding damaging effects may not be that easy if you’re Incapacitated or can’t cast spells.

The constant elements represent the continual threat a trap poses. Active and constant elements may blend together and that may make it hard to identify them sometimes. The example provided, for instance, shows that while the saw blades get to attack on their initiative, the players also take damage from them at the end of each of their turns, if they stay near them.

A very interesting part of complex traps is their dynamic elements. These can appear in various forms and be triggered with as many as you can think. For example, a dynamic element is the water that is rising slowly in the room or the increasing speed of the swirling blades.

The best thing about dynamic elements, in my opinion, is that they can add the sense of urgency. You may have found the perfect spot on the hallway so the blades can’t get you, but you can’t stay here forever if, for example, poisonous gas keeps flowing inside the room, dealing damage that increases each turn.

Nothing really is different for the triggers of complex traps. They may be more than one and even harder to spot but that’s just it.

Complex traps can be slowfast, or very fast. A slow trap acts on an initiative of 10, a fast one on an initiative of 20, and a very fast acts twice, once on an initiative of 10 and once on a 20. Different speeds provide different options. Slow ones can be used along with monsters, while very fast ones are not so friendly to creatures standing close to them.

Disarming a complex trap can be a form of a skill challenge. One success while trying to disarm the trap may make it less deadly. I started playing playing D&D a couple of months before 5th Edition came out so my first impression of the game were with 4e. Skill challenges were one of my favorite things to use in my games.

A problem with this is that the disarming skill challenge may be interesting for the character disarming the trap, but the rest of them shouldn’t just sit and stare at them while they work. Think of ways everyone can help and also promote improvisation. Could a Wall of Force destroy the swirling blades over the mechanism the rogue has to approach in order to disarm the part?

Finally, like with the simple traps, I’ll quickly go over the three complex traps provided as examples.

  • Path of Blades. The use of the Rune of Fear is quite mean here. My favorite part of this trap are the dynamic elements, and especially the blade miss.
  • Sphere of Crushing Doom. Thinking with portals can always lead to interesting ideas. This traps has only one active element but, honestly, it’s enough. Since I have played the Portal games, the dynamic element made me chuckle. Also, I really like the fact that there are various ways to disarm the trap.
  • Poisoned Tempest. This is an example of a good use of the falling gate trap. It also shows that you can have multiple effects generated from one element.

This week’s Unearthed Arcana is quite good, and definitely much better than last week’s. The design rules of the traps, while not flawless, are straightforward. I’d like to see a refined version of these rules in the future. I suggest giving the document a read or two before trying to create complex traps because it may become a bit confusing if you’re not that experienced of a DM.

You can check out the full article here. And don’t forget, the survey about last week’s mass combat rules can be found here.

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