Legendary Resistance (3/Day). If she fails a saving throw, she can choose to succeed instead.

Hovering. Wraith floats about a foot or so off of the ground. Although she cannot go any higher than this when walking, this ability can be useful in simply avoiding certain things completely. In the event Wraith is in the air, most likely from her using her 'Light Dash' or falling off of a point of elevation, she would act as if she were under the effect of 'Feather Fall'.
ex: Grease Spell, Pressure Plates, Low-Strung Trip-Wires, Ball Bearings, Caltrops, etc.

Multiattack. Wraith can use Terrifying Visage and makes three cleave attacks with her bladed arms.

Cleave. Melee Weapon Attack: +6 to hit, reach 10ft., 1 target. Hit: 10 (2d10+ 3) Slashing damage. 

Terrifying Visage. Each creature of Wraith's choice that is within 120 feet of her and is aware of her must succeed on a DC 16 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. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Wraith's Terrifying Visage for the next 24 hours.

Warp Blast (Recharge 5-6). Wraith dashes in a flash of light to a location it chooses within 60ft.

Upon arriving, Wraith's skin bubbles, and suddenly the explodes in a flash of light, dealing (6d6 + 6) force damage. All creatures within 10 ft. of Wraith must make a DC 16 Constitution Saving throw, on a success, they take half damage instead. On a failure, they take full damage and are sent 10 ft. flying away from Wraith, and are rendered prone.

Abduction (Recharge 6). Melee Weapon Attack: +8 to hit, reach 120ft., 1 target. Hit: 10 (2d10+ 3) Slashing damage. The Target is then grappled. Wraith chooses a target that she can see within 120ft. If she has a clear path towards the target, she can dash directly to them, arms outstretched, and grab them. If this attack hits, the Wraith can choose to dash all the way back to her previous position.

Decoy (Recharge 6). Wraith spawns a dangerous identical clone of herself that attacks targets. With the Decoy deployed, Wraith becomes invisible. She loses the Invisibility if she uses an attack action. 
The clone only has the Cleave and Light Dash actions. It can still hover, of course. Its AC however, stays the same. The clone only does half of the damage that the normal Wraith can. If the clone takes more than 50 Damage total, it disintegrates in a dazzle of light.
If Wraith takes damage while invisible she will flicker for a brief moment, before returning to invisibility. The Decoy is only active until the end of Wraith's next turn.

Supernova (Recharge 6). Wraith enters a frenzied state until the start of her next turn. While in this form, all of her melee attacks deal an extra (2d4) force damage, and she gets to do one extra attack on her turn. She also gets 2 reactions in this state, instead of one. 

Wraith can take 3 legendary actions, choosing from the options below. Only one legendary action option can be used at a time and only at the end of another creature's turn. Wraith regains spent legendary actions at the start of its turn.

Light Dash (Costs 1 Legendary Action). Wraith dashes in a flash of light to a location it chooses within 60 feet.