“I have a passive Perception of 30. Where are all the traps?” Every GM has had this problem where one character specializes in a skill so much that it potentially renders traps irrelevant in their game without setting absurd DCs to find them. While setting extremely high DCs gives that player the occasional challenge, it minimizes any impact that other characters can offer when there is a trap.
One way to handle this problem is to vary the ways in which your traps are detected, such as using traps that are obvious or using natural hazards. This adds variety, allows the optimized PC to occasionally be surprised, and allows a trap that can be located by multiple skills to involve other characters in the fun.
Let’s consider some of the most likely skills and what they are intended for:
- Arcana: Arcana is used to recognize spells and magical runes. If the floor is covered in arcane runes, there is no check needed to see them. They are right there, but an arcana check might note that only one of them is actually a ward.
- History (or Stonecunning Trait): If a trap is stone-based and an exemplar of a particular culture’s work, you might allow History or characters with the Stonecunning trait to recognize it.
- Investigation: Investigation is for putting clues together. Rather than locating something that you cannot see right away, Investigation lets you recognize things right in front of you as valuable. For example, the floor is warped and melted in front a statue that also shows some damage. It is likely acid comes out of the hole in the statue. Sometimes, you might be able to locate something hidden by connecting it with something that you can see without searching. That quarter-circle scuff mark worn in the floor suggests a secret door opens toward you.
- Perception: Perception is intended to spot or hear things that are hidden or otherwise difficult to observe. If you might not know it’s there, Perception is how you find it. Note that Perception doesn’t automatically tell you how something works. It just helps you locate it. If there is a hidden pressure plate in a tiled floor, Perception is how you spot that a tile is different from the others.
- Survival: Survival works well for those “traps” that are natural hazards. That pile of rocks is obvious, but Survival could tell you that it’s unstable and might fall if walked next to.
Simple trap (level 1–4, moderate threat)
While traveling through a swampy area, a side trail leads off 30 feet from the main trail to a small stone altar atop a dry rise. Unfortunately, the trail has specifically been cut through an area of bog that cannot support significant weight.
Trigger. An area of quaking bog—an unstable area of vegetation floating over water—surrounds the hill for 20 feet. Any creature weighing more than 30 pounds that walks across the area must succeed on a DC 10 Dexterity saving throw to leap back. Those that fail break through the vegetation and begin sinking.
Effect. A creature that breaks through the vegetation sinks 1d4 + 1 feet into the sucking mud below and becomes restrained. At the start of each of the creature’s turns, it sinks another 1d4 feet. As long as the creature isn’t completely submerged, it can escape by using its action and succeeding on a Strength check (DC 10 + the number of feet the creature has sunk into the bog). A creature can gain advantage on their next check by spending a round cutting themselves free of the vegetation’s roots and vines by doing 10 points of slashing damage. The rules for escaping otherwise mirror those for quicksand.
Countermeasures. A successful DC 10 Wisdom (Survival) check notes the area is an unstable bog.
Simple trap (level 5–10, dangerous threat)
The entirety of this dark room is covered in a thick layer of dust. There are freshly dipped, unlit torches on the walls and a candelabra with half-used candles next to the door. The walls show significant soot near all the torches and candles, typical of frequent use.
Trigger. Lighting a torch, candle, or bringing an open flame into the room as the dust is stirred up causes it to explode.
Effect. Each creature within 20 feet of the door must make a DC 15 Dexterity saving throw. A creature takes 8d6 fire damage on a failed saving throw or half as much damage on a successful one.
Countermeasures. A successful DC 15 Intelligence (Investigation) check notes that the soot patterns do not match a normal burn pattern but look more indicative of an explosion. A second successful DC 15 Intelligence (Investigation) check notes that the soot does not smell like normal dust but rather of something alchemical and similar to the odor of pitch coming from the fresh torches.
Writing on the Wall
Simple trap (level 5–10, dangerous threat)
The walls, floor, and ceiling of this 50-foot-long corridor are covered in glyphs. The glyphs are easy to see and not hidden in any way. All are non-magical references to fire except for one, and that one is a magical trap.
Trigger. Stepping within 10 feet of the door at the end of the hallway triggers an explosion of acid.
Effect. Each creature within 20 feet of the door must make a DC 15 Dexterity saving throw. A creature takes 5d8 acid damage on a failed saving throw or half as much damage on a successful one.
Countermeasures. A successful DC 15 Intelligence (Arcana) check notes the glyphs are all non-magical references to fire except for the last glyph, in front of the door at the end of the hallway, which is typically used in magic that does acid damage. The glyph can also be detected with a detect magic spell and can be dispelled as a 3rd-level spell using dispel magic.