Unexpected Traps for Unsuspecting Characters | 5e Traps

December 16, 2023
Posted by Luke Hart

By Zac Chaney

Looking for some cool 5e traps you can drag and drop into your game to give your players a fun little surprise? Or perhaps your BBEG has a treasure hoard to protect? These 5e traps can help!

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Unexpected Traps for Unsuspecting Characters

These three traps are designed to be unexpected and work in unusual ways. You can change and adapt them as needed depending on the level you’re running them for or use them as-is. When placing these traps, consider where they can have the highest impact. Most traps are designed to detect people who don’t belong, so they won’t be placed in a random hallway nobody is likely to enter.

Mirror, Mirror on the Wall

Mechanical trap (Simple trap, level 11-16, dangerous)

Description. This trap is intended to be a deception within a deception. There’s a lightly enchanted mirror on the wall designed to look and act like a magic mirror; however, it’s anything but—it is actually a dangerous gas trap meant to lure in and neutralize intruders.

Trigger. If one or more characters stand in front of the mirror, it releases gas into the room.

Effect. A sickly green gas expels from the mirror and fills the room up to a 30-foot radius. All creatures within this area must succeed on a DC 17 Constitution saving throw. On a failure, they take 55 (10d10) acid damage and are paralyzed for one minute. On a success, they take half as much damage and are not paralyzed. The gas lingers for 15 seconds before dissipating into the air.

Countermeasures. If the characters succeed on a DC 17 Wisdom (Perception) check, they’ll notice small holes in the side of the mirror. Plugging these holes will prevent the gas from being released. Alternatively, if the characters use a spell like alter self to disguise themselves as the mirror’s owner, they can make a DC 15 Charisma (Performance) check to make the mirror deactivate.

Asteroid Impact

Mechanical trap (Simple trap, level 17-20, deadly)

Description. This is an extremely simple trap, though difficult to set up. Hidden in the clouds above the trapped location is a massive rock, close to the size of a building. Whoever sets this trap up knows what it takes to kill powerful adventurers and spares no expense to do it.

Trigger. When the characters step in the right place, the enchantment holding the rock in the air is dispelled, and it comes hurling toward the characters.

Effect. When the rock falls to the ground, it creates a massive impact. Any buildings within 100 feet of the impact site are destroyed, and any within 1000 feet suffer damage. The characters and any other creatures within 100 feet of the impact site must make a DC 20 Dexterity saving throw, or take 66 (12d10) bludgeoning damage and 66 (12d10) fire damage, or half as much on a success.

Countermeasures. This trap is a simple but effective way of dealing with high-level characters and is straightforward to disarm (though not easy!). If the characters succeed on a DC 20 Wisdom (Perception) check near the trigger location, they will notice a series of pressure plates covering the whole area. If they succeed on a DC 25 Dexterity (Thieves’ Tools or Sleight of Hand) check, they will disarm the plates.

Cave-in

Dungeon hazard (Complex trap, 5-10, setback)

While this trap is technically just a setback, it can be far more dangerous depending on the size of the cave. Consider how long it will take for the characters to escape; if it looks like it might not be realistically possible, consider whether to lower the damage or frequency of the rockfall.

Description. This hazard serves as an alternative way to run a cave-in. It aims to challenge characters as they try to run and escape from the cave falling apart around them. However, as a hazard, clever characters may be able to mitigate it and prevent the cave’s collapse.

Trigger. Anything that suits the game can cause the cave to begin collapsing. Common options include a certain amount of damage dealt to the cave, certain types of damage, or defeating a major villain at the end of the cave.

Initiative. This hazard acts on initiative counts 20 and 10.

Active Elements. Rocks and rubble begin to fall from the ceiling, shrinking the cave and potentially trapping the characters. While it’s collapsing, the ground shakes with the force of the rocks hitting it.

Rockfall (Initiative 20). Rocks falling create a direct hazard to the characters as they attempt to escape. Each character within the cave must succeed on a DC 13 Dexterity saving throw to avoid the rocks, taking 2d10 bludgeoning damage on a failure. Affected creatures must make a DC 13 Strength saving throw to avoid being knocked prone by the rocks.

Ground Tremors (Initiative 10). The ground shakes violently as the rocks are falling. All characters inside the cave must make a DC 15 Dexterity saving throw to avoid treating the cave as difficult terrain for the next round.

Dynamic Elements. The rockfall and tremors gradually increase in intensity until the entire cavern collapses.

Growing Intensity. Every three rounds, the DC of the rockfall and ground tremors increases by 1.

Countermeasures. This hazard is difficult to counter but not impossible. If the characters spend at least 1 hour and succeed on a DC 20 Intelligence (Investigation), Wisdom (Perception), and Dexterity (Mason’s Tools) check, they will be able to stabilize a section of the cave. This must be repeated for each section the characters want to stabilize. Each character may only make one check per section, but if one fails, another may attempt it instead.