Arachnacht

Fear Aura. Any creature that starts its turn within 10 feet of the Arachnacht must succeed on a DC 18 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success,

Nightmare Weaver. As an action, the Arachnacht can cast the spell Phantasmal Killer (DC 18) at will, targeting one creature it can see within 120 feet. At the end of the targeted creature's turn, they must succeed on a DC 18 Wisdom saving throw or take 4d10 damage.

Multiattack. The Arachnacht makes two attacks: one with each of its claws.

Claws. Melee Weapon Attack: +10, reach 10 ft, one target. Hit: 18 (2d10+7) slashing damage plus 10 (3d6) psychic damage. 

Web (Recharge 5-6). Ranged Weapon Attack: +9, range 30/60 ft., one creature. On a hit, the target is restrained by webbing. As an action, the restrained target can make a DC 18 Strength check, bursting the webbing on a success. The webbing can also be attacked and destroyed (AC 16; HP 30; vulnerability to fire damage; immunity to bludgeoning, poison, and psychic damage).

Shadow Cloak. The Arachnacht envelops itself in darkness, granting it partial concealment until the start of its next turn. While under the effect of Shadow Cloak, attacks against the Arachnacht have disadvantage, and it gains advantage on Dexterity (Stealth) checks to hide.

Shadow Step. The Arachnacht teleports to an unoccupied space that that it can see up to 60 feet away.

Terrifying Presence (Costs 2 Actions): The Arachnacht uses its Fear Aura. Each creature within 30 feet of the Arachnacht must succeed on a DC 18 Wisdom saving throw or become frightened for 1 minute.

Nightmarish Assault (Costs 2 Actions): The Arachnacht targets one creature it can see within 60 feet of it. The target must make a DC 18 Wisdom saving throw or be subjected to a vision of its worst fear, taking (3d10) psychic damage and becoming frightened for 1 minute on a failed save. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.