Magic Resistance.

The vargouille has advantage on saving throws against spells and other magical effects.

Actions

Bite.

Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage plus 10 (3d6) psychic damage.

Abyssal Curse.

The vargouille targets one Humanoid within 5 feet of itself that has the incapacitated condition. The target must succeed on a DC 12 Charisma saving throw or become cursed. The cursed target's Charisma decreases by 1 after each hour, as its head takes on fiendish aspects, and its Charisma can't increase. The curse doesn't advance while the target is in sunlight or the area of a daylight spell. When the cursed target's Charisma becomes 2, the target dies, and its head tears from its body and becomes a new vargouille reflection. Casting remove curse, greater restoration, or a similar spell on the target before the transformation is complete ends the curse and restores the target's Charisma.

Horrific Reflection (Recharge 5–6).

The vargouille's head mimics that of a Humanoid the vargouille can see within 120 feet of itself. The target must succeed on a DC 12 Wisdom saving throw or take 10 (3d6) psychic damage and have the frightened condition for 1 hour or until the vargouille loses concentration (as if concentrating on a spell). If the target's saving throw is successful or if the effect ends on it, the target is immune to the Horrific Reflection of all vargouille reflections for 1 hour.

Vargouille Reflection