Actions

Multiattack. The matriarch makes two claws attacks.
Claws. Melee Weapon Attack: +6 to hit, reach 5 ft., one target. Hit: 13 (3d6 + 3) slashing damage.

Fleeting Form. The matriarch can magically disguise itself to resemble a humanoid of roughly similar size and shape for up to 1 hour. It can revert to its true form as a bonus action. This illusion does not hold up to close scrutiny.

Luring Song. The matriarch sings a magical melody. Every humanoid and giant within 300 feet of the matriarch that can hear the song must succeed on a DC 14 Wisdom saving throw or be charmed until the song ends. The matriarch must take a bonus action on its subsequent turns to continue singing. It can stop singing at any time. The song ends if the matriarch is incapacitated.
While charmed by the matriarch, a target is incapacitated and ignores the songs of other harpies. If the charmed target is more than 5 feet away from the matriarch, the target must move on its turn toward the matriarch by the most direct route, trying to get within 5 feet. It doesn't avoid opportunity attacks, but before moving into damaging terrain, such as lava or a pit, and whenever it takes damage from a source other than the matriarch, the target can repeat the saving throw. A charmed target can also repeat the saving throw at the end of each of its turns. If the saving throw is successful, the effect ends on it. A target that successfully saves is immune to this matriarch's song for the next 24 hours.

Visage of Desire (1/Day). The matriarch projects a vision into the minds of creatures within 30 feet of it that aren't constructs or undead, showing each creature achieving whatever it most desires. An affected creature must succeed on a DC 14 Wisdom saving throw or drop whatever it is holding and become paralyzed until the end of its next turn.