Shadow Sibling

Crafted by Dyrrn the Corruptor, this black jewel-like object fuses to the center of your forehead when you attune to it. As a Bonus Action, you can cause the sibling to exude or retract an ectoplasmic shadow that surrounds your body and conceals you from prying eyes. While the shadow is active, Wisdom (Perception) checks made to see you have Disadvantage, and you have Advantage on Dexterity (Stealth) checks made to Hide.
In addition, when you are hit by an attack, you can take a Reaction to expend one Hit Die to shield yourself. Roll the die and add the result to your AC, including against the triggering attack. This bonus lasts until the end of your next turn.