Restriction: This ability can be applied only to heavy armor.
When the wearer of unbowed armor would be reduced to 0 hit points or fewer by an attack that deals hit point damage, the wearer can negate all of that attack’s damage as an immediate action. Using this effect permanently destroys the unbowed armor and causes it to explode in a shower of metal shrapnel, dealing 1d6 points of piercing damage per point of armor bonus feats to AC granted by the armor. This damage affects all creatures within 10 feet of the wearer (but not the wearer herself). A successful DC 20 Reflex save halves this damage.
Pathfinder Player Companion: Armor Master’s Handbook © 2016, Paizo Inc.; Authors: Alexander Augunas, Robert Brookes, Anthony Li, Luis Loza, and David Schwartz.