Dark Serpent's Luck. When Yuki makes an ability check or saving throw, she can add a d10 to the roll. It can do this after the roll is made but before any of the roll’s effects occur.

Whispering Aura. At the start of each of Yuki's turns, each creature of its choice within 15 feet of it must succeed on a DC 20 Wisdom saving throw or take 10 (6d6) psychic damage, provided the warlock isn’t incapacitated.

Multiattack. Yuki makes three Serpent's Strike attacks.

Serpent's Strike. Melee or Ranged Attack Roll: +15, reach 10 ft. or range 120 ft. Hit:  (4d10 + 5) Psychic damage plus 17 (2d6) Piercing damage, and the target has the Frightened condition until the start of Yuki's next turn.

Serpent's Void. Yuki opens a momentary extra-planar rift within 120 feet of her. The rift is a serpent-filled, 40-foot cube. Each creature in that area must make a DC 21 Wisdom saving throw. On a failed save, a creature takes  (6d10) 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.

Dark Queen's Rebuke (6/Day). In response to being damaged by a visible creature within 60 feet of it, Yuki forces that creature to make a DC 20 Constitution saving throw, taking 22 (5d10) necrotic damage on a failed save, or half as much damage on a successful one.

Misty Escape (4/Day). In response to taking damage, the warlock turns invisible and teleports, along with any equipment it is wearing or carrying, up to 60 feet to an unoccupied space it can see. It remains invisible until the start of its next turn or until it attacks, makes a damage roll, or casts a spell.