If you hold this beetle-shaped medallion in your hand for 1 round, an
inscription appears on its surface revealing its magical nature. It
provides two benefits while it is on your person:
You have advantage on saving throws against spells.
The scarab has 12 charges. If you fail a saving throw against a
necromancy spell or a harmful effect originating from an undead
creature, you can use your reaction to expend 1 charge and turn the
failed save into a successful one. The scarab crumbles into powder and
is destroyed when its last charge is expended.
Geiriadur