Your cave-delving reactions can save you from a sudden misstep or a serious injury.

Encounter   ✦     Martial
Immediate Interrupt      Personal

Trigger: You take damage from a trap, a hazard, or a fall.

Effect: Reduce the damage by 5 + one-half your level.
    Level 11: 10 + one-half your level.
    Level 21: 15 + one-half your level.

Published in Into the Unknown: The Dungeon Survival Handbook, page(s) 14.