Multiattack

The ambassador uses its Withering Stare. It then makes three rapier attacks.

Rapier

Melee Weapon Attack: +8 to hit, reach 5 ft. Hit: 8 (1d8 + 4) piercing damage plus 10 (3d6) cold damage.

Honeyed Words (Recharges after a Long Rest)

The silver-tongued shadow fey ambassador weaves together a string of highly persuasive and agreeable words. Each creature within 30 feet of the ambassador must succeed on a DC 16 Wisdom saving throw or be charmed by the ambassador, regarding it as a wise and trustworthy ally with the creature's best interests at heart. A charmed target doesn't have to obey the ambassador's commands, but it views the ambassador's words in the most favorable way. Each time a charmed target witnesses the shadow fey ambassador or its allies do something harmful to the target or its companions, it can repeat the saving throw, ending the effect on itself on a success. Otherwise, the effect lasts as long as the ambassador maintains concentration, up to 8 hours.

Withering Stare

The shadow fey ambassador targets one creature it can see within 30 feet of it. If the target can see it, the target must succeed on a DC 16 Wisdom saving throw or be frightened for 1 minute. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to the ambassador's Withering Stare for the next 24 hours.