Revenant's Shawl

This shawl is made of old raven feathers woven together with elk sinew and small bones. When you are reduced to 0 hit points while wearing the shawl, it explodes in a burst of freezing wind. Each creature within 10 feet of you must make a DC 13 Dexterity saving throw, taking 4d6 cold damage on a failed save, or half as much damage on a successful one. You then regain 4d6 hit points, and the shawl disintegrates into fine black powder.