Vivixeen, Cursed Caretaker

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

Petrifying Gaze. When a creature that can see Vivixeen's eyes starts its turn within 30 feet of the medusa, Vivixeen can force it to make a DC 14 Constitution saving throw if Vivixeen isn't incapacitated and can see the creature. If the saving throw fails by 5 or more, the creature is instantly petrified. Otherwise, a creature that fails the save begins to turn to stone and is restrained. The restrained creature must repeat the saving throw at the end of its next turn, becoming petrified on a failure or ending the effect on a success. The petrification lasts until the creature is freed by the greater restoration spell or other magic.

Unless surprised, a creature can avert its eyes to avoid the saving throw at the start of its turn. If the creature does so, it can't see the medusa until the start of its next turn, when it can avert its eyes again. If the creature looks at Vivixeen in the meantime, it must immediately make the save.

If Vivixeen sees herself reflected on a polished surface within 30 feet of it and in an area of bright light, Vivixeen is, due to her curse, affected by her own gaze.

Magic Resistance.  Vivixeen has advantage on saving throws against spells or magical effects. 

Innate Spellcasting. Vivixeen spellcasting ability is Intelligence(spell save DC17). Vivixeen can innately cast the following spells, requiring no material components: 

At will: Dispel Magic, Detect Magic, Sending, Detect Thoughts, Misty Step

4/Day each: Psychic Lance, Dissident Whispers, Lightning Bolt

Multiattack. Vivixeen makes either three melee attacks--one with her snake hair and two with her shortsword--or two ranged attacks with her longbow.

Snake Hair. Melee Weapon Attack: +8 to hit, reach 5 ft., one creature. Hit: 4 (1d4 + 2) piercing damage plus 14 (4d6) poison damage.

Shortsword. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage.

Longbow. Ranged Weapon Attack: +10 to hit, range 150/600 ft., one target. Hit: 6 (1d8 + 2) piercing damage plus 7 (2d6) poison damage.

Vivixeen 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. Vivixeen regains spent legendary actions at the start of his turn.

Snake Head.  Vivixeen Makes and attack with one of her snake heads. 

Psionics. Vivixeen uses Psychic Step or Spellcasting

Telekinetic Fling (Cost 2 Actions). Vivixeen chooses one Medium or smaller object that isn't being worn or carried that it can see within 60 feet of it, and it magically hurls the object at a creature it can see within 60 feet of the object. The target must succeed on a DC 18 Dexterity saving throw or take 18 (6D6) bludgeoning damage.