7th-level Fey Wanderer feature
The magic of the Feywild guards your mind. You have advantage on saving throws against being charmed or frightened.
In addition, whenever you or a creature you can see within 120 feet of you succeeds on a saving throw against being charmed or frightened, you can use your reaction to force a different creature you can see within 120 feet of you to make a Wisdom saving throw against your spell save DC. If the save fails, the target is charmed or frightened by you (your choice) for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a successful save.