Shapechanger. The fiend can use a bonus action to polymorph into a Small or Medium humanoid, or back into its true form. It can also create illusory clothes, equipment or items which disapears when handled by anyone else. Without wings, the fiend loses its flying speed. Other than its size and speed, its statistics are the same in each form.. It reverts to its true form if it dies.

Illusion Magic. As a bonus action you create the image of an object, a creature, or some other visible phenomenon that is no larger than a 20-foot cube. The image appears at a spot that you can see within a 120ft range and lasts for the 10 minutes or until you dismiss it with a bonus action. While you are creating the illusion you are unable to cast any other spells.

The image seems completely real, including sounds, smells, and temperature appropriate to the thing depicted. You can't create sufficient heat or cold to cause damage, a sound loud enough to deal thunder damage or deafen a creature, or a smell that might sicken a creature (like a troglodyte's stench).

As long as you are within range of the illusion, you can use your bonus action to cause the image to move to any other spot within range. As the image changes location, you can alter its appearance so that its movements appear natural for the image. For example, if you create an image of a creature and move it, you can alter the image so that it appears to be walking. Similarly, you can cause the illusion to make different sounds at different times, even making it carry on a conversation, for example.

Physical interaction with the image reveals it to be an illusion, because things can pass through it. A creature that uses its action to examine the image can determine that it is an illusion with a successful Intelligence (Investigation) check against a save DC 17. If a creature discerns the illusion for what it is, the creature can see through the image, and its other sensory qualities become faint to the creature.

Claw (Fiend Form Only). Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 6 (1d6 + 3) slashing damage.

Charm. One humanoid the fiend can see within 30 feet of it must succeed on a DC 15 Wisdom saving throw or be magically charmed for 1 day. The charmed target obeys the fiend's verbal or telepathic commands. If the target suffers any harm or receives a suicidal command, it can repeat the saving throw, ending the effect on a success. If the target successfully saves against the effect, or if the effect on it ends, the target is immune to this fiend's Charm for the next 24 hours.

The fiend can have only one target charmed at a time. If it charms another, the effect on the previous target ends.

Draining Kiss. The fiend kisses a creature charmed by it or a willing creature. The target must make a DC 15 Constitution saving throw against this magic, taking 5d6 psychic damage on a failed save, or half as much damage on a successful one. The target's hit point maximum is reduced by an amount equal to the damage taken. This reduction lasts until the target finishes a short rest. The target dies if this effect reduces its hit point maximum to 0.

Etherealness. The fiend magically enters the Ethereal Plane from the Material Plane, or vice versa.