Amulet of Chance

This amulet, usually adorned with a depiction of Istus, the goddess of fate and destiny, grants its wearer the ability to use their reaction to cause an enemy within 15 ft. to reroll any successful attack or saving throw once. The target must take the lower result, even if it still succeeds. The amulet has two charges. If the charges are used, the amulet becomes a standard necklace worth 25 gp and cannot be used again until enchanted by a magic caster of high enough level.