Traps in Play (2014)

When adventurers come across a trap, you need to know how the trap is triggered and what it does, as well as the possibility for the characters to detect the trap and to disable or avoid it.
Triggering a Trap
Most traps are triggered when a creature goes somewhere or touches something that the trap's creator wanted to protect. Common triggers include stepping on a pressure plate or a false section of floor, pulling a trip wire, turning a doorknob, and using the wrong key in a lock. Magic traps are often set to go off when a creature enters an area or touches an object. Some magic traps (such as the Glyph of Warding spell) have more complicated trigger conditions, including a password that prevents the trap from activating.
Detecting and Disabling a Trap

Trap Effects
The effects of traps can range from inconvenient to deadly, making use of elements such as arrows, spikes, blades, poison, toxic gas, blasts of fire, and deep pits. The deadliest traps combine multiple elements to kill, injure, contain, or drive off any creature unfortunate enough to trigger them. A trap's description specifies what happens when it is triggered.
The attack bonus of a trap, the save DC to resist its effects, and the damage it deals can vary depending on the trap's severity. Use the Trap Save DCs and Attack Bonuses table and the Damage Severity by Level table for suggestions based on three levels of trap severity.
A trap intended to be a setback is unlikely to kill or seriously harm characters of the indicated levels, whereas a dangerous trap is likely to seriously injure (and potentially kill) characters of the indicated levels. A deadly trap is likely to kill characters of the indicated levels.
Trap Save DCs and Attack Bonuses
| | Trap Danger | Save DC | Attack Bonus
| Setback | 10-11 | +3 to +5
| Dangerous | 12-15 | +6 to +8
| Deadly | 16-20 | +9 to +12

Damage Severity by Level
| | Character Level | Setback | Dangerous | Deadly
| 1st-4th | 1d10 | 2d10 | 4d10
| 5th-10th | 2d10 | 4d10 | 10d10
| 11th-16th | 4d10 | 10d10 | 18d10
| 17th-20th | 10d10 | 18d10 | 24d10

Complex Traps
Complex traps work like standard traps, except once activated they execute a series of actions each round. A complex trap turns the process of dealing with a trap into something more like a combat encounter.
When a complex trap activates, it rolls initiative. The trap's description includes an initiative bonus. On its turn, the trap activates again, often taking an action. It might make successive attacks against intruders, create an effect that changes over time, or otherwise produce a dynamic challenge. Otherwise, the complex trap can be detected and disabled or bypassed in the usual ways.
For example, a trap that causes a room to slowly flood works best as a complex trap. On the trap's turn, the water level rises. After several rounds, the room is completely flooded.