Cobalt Harpy Enchantress

Spellcasting. The harpy is a 5th-level spell caster. Its spell casting ability is Charisma (spell save DC 11, +3 to hit with spell attacks). The harpy knows the following sorcerer spells:

Cantrips (at will): blade ward, chill touch, dancing lights, ray of frost, true strike

1st Level (4 slots): witch bolt, magic missile, chromatic orb

2nd Level (3 slots): shatter, blur

3rd Level (2 slots): dispel magic

*The harpy casts blur on itself before combat, if not surprised. 

Claws. Melee Weapon Attack: +3 to hit, reach 5 ft., one target. Hit: 6 (2d4 + 1) slashing damage.

Slumber Song. The harpy sings a magical melody. Every humanoid and giant within 300 feet of the harpy that can hear the song must succeed on a DC 11 Wisdom saving throw or fall asleep until the song ends. The harpy must take a bonus action on its subsequent turns to continue singing. It can stop singing at any time. The song ends if the harpy is incapacitated.

While put to sleep by the harpy, a target is incapacitated. A sleeping target can repeat the saving throw at the end of each of its turns. If the saving throw is successful, the effect ends on it, but it remains asleep until jostled or injured. A sleeping target may also repeat the saving throw if it is injured by the harpy or one of its allies. 

A target that successfully saves is immune to this harpy's song for the next 24 hours.