Handling Traps with Skills in 5E

Here is a quick summary of how to handle traps with skills in 5E. Each step in this feeds the next step.

1. Passive Perception -- Allows a PC to notice obvious scents (acid vapor), sounds (click), feelings (floor seems suddenly uneven), and sights (is that a tripwire or a spiderweb) that may or may not indicate a trap. Be sure to have them notice things when there isn't a trap too.
2. Active Perception -- Allows PCs to actively search for other trap clues. This requires a roll and perhaps, an action. Active perception usually does not involve touching anything, except to taste.
3. Investigation -- Allows a PC to investigate a specific thing that was identified with perception. The player should describe what they do based on the scenario. They may choose to touch and interact with things. This could set off the trap. Investigation, if successful, can determine how the trap works and what the trap does. Some traps have hidden components or components far away that limit the results. Some traps have magical elements that must be deciphered using another check (History or Arcana are likely choices).
4. Sleight of Hand -- The PC can use information gained through investigation (best) or perception (limited) to attempt to set off or disable the trap. Their actions should be described to determine the outcome of their action.

To support this a trap is defined by:

• A Reason for the trap. They can be placed to keep someone out, to keep someone in, to kill or to injure, or even as just a natural occurrence (loose rocks in an old tunnel). Make sure the location fits with the reason for the trap, if it is intentional.
• A Notice DC to (passively) notice the something that could be a trap (tripwire, acid smell, shiny object, brick out of place, etc)
• A Perception DC to see the trap when actively looking. This should be easier that the Notice DC.
• An Investigation DC to determine how the trap works and/or what it does. Some information may be unavailable if the parts can't be sensed or are far away.
• Optionally, an Arcana or History Check DC to descipher magical elements of the trap.
• A Sleight of Hand DC to disable or set off the trap.
• The Trigger condition for the trap. This can be a single condition (step on a pressure plate, someone pulls a lever), or a series of conditions, possibly separated in time or space (stepping on the pressure plate twice, or stepping on two separate pressure plates).
• The Effect or Damage that the trap does, where this effect or damage occurs, and how the target(s) avoid the damage (save DC or attack vs AC).
• Whether or not the trap Resets, and when it resets (automatically, perhaps after a period of time, or when a lever is pulled)

Trap effects can be combines or layered. For example, one trap could set off another trap. Also a simple trap could have a more complex trap hidden in it, such that the more complex trap is set off when the easier trap is disabled.