Banshee Reverent

Spirit of the Night. The Banshee Reverent only appears once the sun goes down. They dissipate in tormented screams upon sunrise. 

Incorporeal Movement. The Banshee Reverent can move through other creatures and objects as if they were Difficult Terrain. It takes 5 (1d10) Force damage if it ends its turn inside an object.

Vibration Sense. The Banshee Reverent can sense vibrations around them, granting them 120 ft Blindsight. 

Innate Spellcasting. The Banshee Reverent's innate spellcasting ability is Charisma (spell save DC 15, +7 to hit with spell attacks). They can innately cast from the spells detailed in their Actions and Reactions, requiring no Somatic or Material components. A Perception Skill Check (DC 15) is required to tell that they are casting. 

Multi-action. The Banshee Reverent can take two actions per turn from their At Will or 3/day spell list. 

At Will Spells:

Chill Touch. Ranged Spell Attack: +7, reach 120 ft. Hit: 9 (2d8) Necrotic damage and it can't regain hit points until the start of your next turn. Until then, the hand clings to the target. If you hit an undead target, it also has disadvantage on attack rolls against you until the end of your next turn.

Claws of Darkness. Melee Spell Attack: +7, reach 10 ft. Hit: 6 (1d10) Cold damage. 

Frightful Start. You twist your visage to scare a creature that you can see within range. The creature must succeed on a Wisdom saving throw (DC 15) or have the Frightened condition until the start of your next turn.

 3/Day Spells:

Bane. Concentration. Up to six creatures of your choice that you can see within range must each make a Charisma saving throw (DC 15). Whenever a target that fails this save makes an attack roll or a saving throw before the spell ends, the target must subtract 1d4 from the attack roll or save.

Call of the Damned. Concentration. The Banshee Reverent wails and summons other damned souls to swarm around them. Each creature that starts its turn or enters into the 30-foot emanation there must make a Wisdom saving throw (DC 15). On a failed save, the target takes (3d6) Psychic damage, and it has the Frightened until sunrise. On a successful save, it takes half as much damage, and it has the Frightened condition until the end of it's current turn. 

Slow. Concentration. The Banshee Reverent alters time around up to six creatures of their choice in a 40-foot cube within range for up to 1 minute. Each target must succeed on a Wisdom saving throw (DC 15) or be affected by this spell for the duration. An affected target’s Speed is halved, it takes a −2 penalty to AC and Dexterity saving throws, and it can’t take Reactions. On its turns, it can take either an action or a Bonus Action, not both, and it can make only one attack if it takes the attack action. If it casts a spell with a Somatic component, there is a 25 percent chance the spell fails as a result of the target making the spell’s gestures too slowly 1d4. An affected target repeats the save at the end of each of its turns, ending the spell on itself on a success.

Counterspell. The Banshee Reverent lets out a silent scream in an attempt to interrupt a creature in the process of casting a spell. The creature makes a Constitution saving throw (DC 15). On a failed save, the spell dissipates with no effect, and the action, Bonus Action, or Reaction used to cast it is wasted. If that spell was cast with a spell slot, the slot isn’t expended.