Each creature of the scylla's choice that is within 100 feet of the Scylla and aware of it must succeed on a DC 21 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to the scylla's Frightful Presence for the next 24 hours.