Band of sacrifice

Band of sacrifice (Wondrous Item, one of a kind)

This eerie band is forged from a metal that shifts and twists at the wearer’s whim, morphing to fit a finger, wrist, or even a horn. Once placed on an appendage it will hold its form. When activated the wielder is granted a single, devastating attack infused with raw, eldritch power. The band then constricts with unnatural force, severing the limb in a flash of crimson light. The greater the sacrifice the greater the power The band constantly whispers to the wearer to be used. After its price is paid it can not be used by the same wielder until it extracts its dark bargain from another living creature.