Warlock of the Great Old One

At the start of each of the warlock's turns, each creature of its choice within 10 feet of it must succeed on a DC 15 Wisdom saving throw or take 10 (3d6) psychic damage, provided that the warlock isn't incapacitated.

The warlock casts one of the following spells, using Charisma as the spellcasting ability (spell save DC 15):

At will: detect magic, guidance, levitate, mage armor (self only), mage hand, minor illusion, prestidigitation

1/day each: arcane gate, detect thoughts, true seeing

The warlock makes two Dagger attacks.

Melee or Ranged Weapon Attack: +6 to hit, reach 5 ft. or range 20/60 ft., one target. Hit: 5 (1d4 + 3) piercing damage plus 10 (3d6) psychic damage.

The warlock opens a momentary extraplanar rift within 60 feet of it. The rift is a scream-filled, 20-foot cube. Each creature in that area must make a DC 15 Wisdom saving throw. On a failed save, a creature takes 9 (2d8) psychic damage and is frightened of the warlock until the start of the warlock's next turn. On a successful save, a creature takes half as much damage and isn't frightened.