Banette

Cursed Body. When hit with a move roll a d4. If you get a 1 or 3 then it will miss.

Ghost. Because it is a ghost, it is immune to any physical attack, like slashing or bludgeoning.

Will-o-Wisp. Banette conjures ghostly fire around one target. It will hit no matter what. It does no damage but it sets the target on fire for five turns. Each turn they take 2d4 fire damage.

Shadow Claw. Melee Weapon Attack: +7 to hit, reach self ft., 1 target. Hit: 1 (3d6 + 4) [necrotic] damage. 

Shadow Ball. RangedWeapon Attack: +7 to hit, range 5/30 ft., 1 target. Hit: 1 (4d6) [Necrotic] damage.

As a bunus action, banette can roll for a stealth check, on a winning throw he can use shadow sneak.

Shadow Sneak. When someone is going to attack banette. It can make a dexterity saving throw of 12. If it suceeds it will turn into a shadow and sneak behind the attacker.