Amulet of Undead Warding

An amulet made of bone and amber fashioned in the shape of a one eyed skull. Contains 3 charges. Expending a charge allows the wearer to become invisible to all undead creatures with an intelligence score of 6 or less for 1 minute. Each turn for the duration, the target becomes visible if they attack or cast a spell. The amulet recovers 1d3 charges after each long rest. If the amulet expends its last charge, roll a d20: on a 1, the amulet shatters and deals 1d10 piercing damage.

Notes: Detection