Amulet of Draining Aegis

This heavy silver amulet features a prominent central gemstone that when worn, lightly pulses in rhythm with the wearer's heartbeat.

Shielding Barrier. While wearing this amulet, when you are hit by an attack or targeted by the Magic Missile spell, you can use your Reaction to cast the Shield spell from the amulet.

Vitality Cost. To cast the spell in this way, you must immediately expend one of your available Hit Dice without regaining hit points or gain one level of Exhaustion.