Elements of a Trap

All traps—mechanical or magical—have the following elements: CR, type, Perception DC, Disable Device DC, trigger, reset, and effect. Some traps might also include optional elements, such as poison or a bypass. These characteristics are described below.

Perception and Disable Device DCs

The builder sets the Perception and Disable Device DCs for a mechanical trap. For a magic trap, the values depend on the highest-level spell used.

Mechanical Trap: The base DC for both Perception and Disable Device checks is 20. Raising or lowering either of these DCs affects the CR (Table 13–3).

Magic Trap: The DC for both Perception and Disable Device checks is equal to 25 + the spell level of the highest-level spell used. Only characters with the trapfinding class feature can attempt a Disable Device check involving a magic trap.

Duration

Unless otherwise stated, most traps have a duration of instantaneous; once triggered, they have their effect and then stop functioning. Some traps have a duration measured in rounds. Such traps continue to have their listed effect each round at the top of the initiative order (or whenever they were activated, if they were triggered during combat).

Reset

A reset element is the set of conditions under which a trap becomes ready to trigger again. Resetting a trap usually takes only a minute or so. For a trap with a more difficult reset method, you should set the time and labor required.

No Reset: Short of completely rebuilding the trap, there’s no way to trigger it more than once. Spell traps have no reset element.

Repair: To get the trap functioning again, you must repair it. Repairing a mechanical trap requires a Craft (traps) check against a DC equal to the one for building it. The cost for raw materials is one-fifth of the trap’s original market price. To calculate how long it takes to fix a trap, use the same calculations you would for building it, but use the cost of the raw materials required for repair in place of the market price.

Manual: Resetting the trap requires someone to move the parts back into place. This is the kind of reset element most mechanical traps have.

Automatic: The trap resets itself, either immediately or after a timed interval.

Bypass (Optional Element)

If the builder of a trap wants to be able to move past the trap after it is created or placed, it’s a good idea to build in a bypass mechanism: something that temporarily disarms the trap. Bypass elements are typically used only with mechanical traps; spell traps usually have built-in allowances for the caster to bypass them.

Lock: A lock bypass requires a DC 30 Disable Device check to open.

Hidden Switch: A hidden switch requires a DC 25 Perception check to locate.

Hidden Lock: A hidden lock combines the features above, requiring a DC 25 Perception check to locate and a DC 30 Disable Device check to open.