Blademail

Armor (medium or heavy), rare This armor has 4 charges. When you are hit with a melee weapon attack while you are attuned to this magical armor, you can use your reaction to expend 1 of its charges and cause the attacker to take damage equal to the damage you took from the attack. The armor regains 1d4 expended charges daily at dawn. If you expend the armor's last charge, roll a d20. On a 1, the blades on the armor twist and bend and are destroyed. A razor-sharp coat of mail, it is the choice of selfless martyrs in combat.