Pit Trap

From Xanathar's Guide to Everything, page 114.

Simple trap (level 1-4, moderate threat)

The simplest of pit traps consists of a 10-foot-deep hole in the floor, concealed by tattered canvas that's covered with leaves and dirt to look like solid ground. This type of trap is useful for blocking off the entrance to a monster lair, and usually has narrow ledges along its sides to allow for movement around it.


 * Trigger: Anyone who steps on the canvas might fall into the pit.
 * Effect: The triggering creature must make a DC 10 Dexterity saving throw. On a successful save, the creature catches itself on the pit's edge or instinctively steps back. On a failed save, the creature falls into the pit and takes 3 (1d6) bludgeoning damage from the fall.
 * Countermeasures: A successful DC 10 Wisdom (Perception) check reveals the presence of the canvas and the 1-foot-wide ledge around the edges of the pit where it is safe to travel.