Armor of undead fortitude (Breastplate)

While attuned to this medium or heavy armor, if damage reduces you to 0 hit points you can make a Constitution saving throw, unless the damage is radiant or from a critical hit. The DC for this saving throw equals 5 plus the damage you took. On a successful save, you drop to 1 hit point instead.

This armor consists of a fitted metal chest piece worn with supple leather. Although it leaves the legs and arms relatively unprotected, this armor provides good protection for the wearer's vital organs while leaving the wearer relatively unencumbered.