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Obvious VS Unexpected

by Jae
obvious vs unexpected

Traps that play on the obvious vs unexpected trope can be fun if used correctly and brutally punishing if used incorrectly. Let’s take a look at how a trap can subvert players’ expectations. Let’s dive straight into the trap.

The Obvious vs Unexpected Boulder Trap

When the players enter the room, they see a long corridor with an ornate pedestal at the end. There are no other doors in this room other than the one the heroes entered from. On the pedestal at the far end there is a piece of treasure with a boulder nested above it. The boulder is obvious due to its size and location, so describe it to your players once they enter the room. Once the players are aware of the boulder, most would assume that the boulder will roll down the corridor if the players take the treasure from the pedestal, which is the assumption of the trap.

Triggering the Trap

When a player takes the treasure from the pedestal, the boulder begins to roll down towards the player. It’s a simple touch trap mechanic. Because of this, players might try a variety of methods to get away from the boulder and likely they will simply seek to outrun it. However, this is the problem of the trap. When the boulder descends to where the platform is, it stops rolling and depresses the pedestal, which triggers the real traps in the walls. These traps are harmless if the player does not run back into them when the trap is triggered. The wall traps can be spikes, flame jets, or anything else that fits the theme of your dungeon. The main point is that it should be something that will affect anyone in the corridor.

Appropriate Trap Use

This trap is used to subvert your players’ expectations and should be used as part of a themed dungeon. Putting this in your average dungeon for kicks and giggles won’t be much fun for your players since they will have no precedent to think it’s anything other than a normal trap. Also worth noting is the kind of place that might have a trap like this; it’s not a normal trap by any means and indicates that the design is specifically to fool hardened adventures.

This kind of trap is best used when paired up with a trickster dungeon. A dungeon that makes everyone second guess their expectations pairs well, and the players will know to look for something that does the opposite of what they might think to expect. Be sure not to use this as the first trap in this kind of dungeon because it can be overly punishing and there was no previous introduction to the obvious vs unexpected dungeon theme.

Rules for the Trap


The boulder should have a low DC to be spotted, if any at all. Think 10 or lower if your party is a low level, or just provide it in the room description. This does two things. First it tips off the players if they roll low but still spot it that it is made to be seen. Second, it tells the players that the trap might have multiple parts if the first is so obvious. The wall traps should have a high perception DC (15+) and should only be revealed if a player actively asks to inspect the rest of the room. While you could just give it to them if they roll high enough, it’s important to have the players think through these kinds of traps. Rolling above a certain number can reveal everything, but the DC can be lowered if players ask to inspect the walls or the pedestal itself.

Trigger Rules

The trap is triggered via touch by magical means. This gives the players the opportunity to detect magic and possibly dispel the traps trigger. This also hides the mechanical components of the trap and deepens the surprise when it is actually triggered. While unlikely, it is also possible for the players to depress the pedestal before touching the treasure, which effectively triggers the mechanical parts of the trap before the magical ones. Allowing for this gives your players another way to disarm the trap and potentially stumble upon a solution.


In regards to damage, the wall traps are the only real danger, but they should not be made to overlap. If you use jets of fire, the player should be hit by no more than one, and they should not be hit constantly during their time in the hall. The damage from this trap (or any trap for that matter) should not be enough to outright kill a player at full health, so when setting damage be sure to check the average HP of your party. If possible, choose to roll many lower sided dice for damage instead of fewer higher sided dice. This makes the trap seem more frightening, artificially increases variation, and brings up the minimum damage without adding anything to the roll.


The players may try a number of ways to disarm the trap. It should be something that can be dispelled. Mechanically, they should be able to depress the pedestal early. The boulder can be held in place in all sorts of ways, but alternatives should be considered dangerous and risky. For example, if a player has an immovable rod and uses that to hold the boulder up. This option works, but good luck getting your immovable rod back. If a Rogue in the party argues that they should be able to take apart the wall or get to the mechanical mechanisms, it’s a good idea to say they could, but it would take many hours of careful work to do so. Remember, you always have the option of saying no to requests like this.


When adding loot to this trap, it needs to be worth it or at least appear to be worth it. Since part of the trap is that it is so obvious, you’ll need to entice your adventurers to want to take the risk of triggering it. Wealth for your party is something that you need to manage on your own, but a good rule of thumb is to make it something that your party can use immediately or something that is a singular valuable object. Both a piece of useful equipment or a golden idol seem equally valuable and can be situational depending on your group and their needs. It could even be a special key that opens up another part of the dungeon.

When Not to Use This Trap

This trap is terrible in a few instances. First and foremost, never use this trap on an overly cautious or paranoid group. It will only serve to feed their paranoia and they will ask to check for traps every five seconds for the rest of the campaign. Secondly, don’t use this trap as a stand-alone. It only works well as a part of a theme. Without proper context, this trap just punishes without adding value. Lastly, never use this trap at the end of a long dungeon before a rest point. It is far too easy for this trap to catch a whole party, and it would feel like a terrible TPK if everyone was low on health.

Fitting the Trap Into Your Games

This trap can be great fun when used in a themed dungeon or brutal if used on its own. If you choose to use this in your game, make sure it will be an appropriate fit and that your players will have a decent chance to solve its mysteries.

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For more walkthroughs and trap examples, check out our Complete Guide to DnD Traps article.

Happy DMing!

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