Dungeons are frequently equipped with deadly mechanical (nonmagical)
traps. A trap typically is defined by its
location and triggering
conditions, how hard it is to
spot before it goes off, how much
damage it deals, and whether or not the heroes receive a
saving throw to mitigate its effects.
Traps that attack with arrows, sweeping blades, and other types of weaponry make normal
attack rolls, with a specific
attack bonus dictated by the trap's design.
Creatures who succeed on a DC 20
Search check detect a simple mechanical
trap before it is triggered. (A simple
trap is a snare, a
trap triggered by a tripwire, or a large
trap such as a pit.)
A character with the trap sense class feature who succeeds on a DC 21 (or higher)
Search check detects a well-hidden or complex mechanical trap before it is triggered. Complex
traps are denoted by their triggering mechanisms and involve pressure plates, mechanisms linked to
doors, changes in weight, disturbances in the air, vibrations, and other sorts of unusual triggers.