Jade Ring of Consume

A tale told about a ring found inside Wave Echo Cave. It was being worn by a skeleton at the bottom of a pool of water.

This jade ring is made a snake consuming itself. It was created for a Yuan-ti priestess to aid in surviving her bizarre rituals. Simply donning the ring grants resistance to psychic intrusion and damage. Upon attunement, the ring tightens around the wearer’s finger with each snake’s fangs ever so slightly piercing the skin.

Upon reaching half of the wearer’s maximum hit points, the snakes begin to twist around the finger constricting rhythmically. The ring will now allow the wearer to tap into their very essence to sustain themselves.

5th Edition Statistics
Resistance vs Psychic damage

Attunement (Long Rest): When below 50% maximum hit point, the wearer may use a Bonus action to roll 1 hit die (expending it) and regain the result + Constitution modifier in hit points.

This may be done with 0 hit dice remaining as well. Upon attempting to use with 0 hit dice, roll as normal, regain the hit points that result but permanently lose that amount of maximum hit points.