Fear Aura

Any hostile target to the creature that starts its turn within 20 feet of the creature must make a Wisdom saving throw (DC = 8 + proficiency bonus + Charisma modifier), unless the creature is incapacitated. On a failed save, the target is frightened until the start of its next turn. If the target’s saving throw is successful, the target is immune to the creature’s Fear Aura for the next 24 hours. (Pit Fiend, pp. 76, MM)