Vannifar, Evolved Enigma

Magic Resistance. Vannifar has advantage on saving throws against spells and other magical effects

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

Anti-Magic Cloak. Vannifar automatically negates the first harmful spell that would affect her each day. Once this feature has been used, her Anti-Magic Cloak becomes inert. 

Aquatic Adaptation.  Vannifar can adapt her body to any aquatic environment, sprouting gills and growing webbing between fingers. She can cast spells underwater and gains a swimming speed equal to her walking speed.

Breathless. Vannifar does not need to breathe. 

Instinctive Attack. When Vannifar casts a spell with a casting time of 1 action, it can make one pseudopod attack as a bonus action.

Spider Climb. Vannifar can climb difficult surfaces, including upside-down on ceilings, without needing to make an ability check.

Regeneration. Vannifar heals 50 hit points on the start of her turn. If Vannifar was hurt by necrotic damage, this trait doesn't function at the start of her next turn. 

Thought Partition. Vannifar is able to rest certain parts of her brain at different times, so she doesn’t need to sleep. She only needs to take a short rest to gain the full benefits of a long rest. She can use this feature only three times in a 24-hour period.

Second Brain. Due to Vannifars' unique brain, she is able to cast two spells per turn. Vannifar can cast an additional spell when she uses an action to cast a spell. Additionally, she can concentrate on any number of spells equal to her spellcasting modifier.

Spellcasting. Vannifar is a 20th-level spellcaster. Her spellcasting ability is Intelligence (spell save DC 19, +14 to hit with spell attacks). Vannifar has the following Wizard spells prepared:
Cantrips (at will): Message, Mage Hand
1st level  Arms of Hadar, Feather Fall, Find Familiar, Magic Missile
2nd level Detect Thoughts, Invisibility, Mirror Image, Blur
3rd level  Counterspell, Fireball, Dispel Magic, Thunder Step
4th level  Blight, Dimension Door
5th level  Cloudkill, Scrying
6th level  Disintegrate, Globe of Invulnerability
7th level  Finger of Death, Planeshift, Forcecage, Crown of Stars
8th level  Dominate Monster, Power Word Stun, Maze, Feeblemind
9th level  Power Word Kill, Wish, Gate, Psychic Scream.

Prime Speaker’s Trident. Melee weapon attack: +10 to hit, reach, range 20/60f5et (2d12+10) piercing damage, and the trident emits a thunderous boom. Each creature in a 15ft cube originating from the prongs of the trident must make a DC 18 Constitution saving throw. On a failed save, the creature takes 3d8 thunder damage and is pushed 10 feet away from Vannifar. If the creature is underwater, the damage is increased by 3d8. On a successful save, the creature takes half as much damage and isn’t pushed.

Paralyzing Touch. Melee Spell Attack: +12 to hit, reach 5 ft., one creature. Hit: (3d6) cold damage. The target must succeed on a DC 18 Constitution saving throw or be paralyzed for 1 minute. The target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success

Pseudopod. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 21 (5d6 + 4) bludgeoning damage plus (5d6) acid damage.

Instinctive Charm. If a creature Vannifar can see makes an attack roll against her while within 30 feet,  she can use a reaction to divert the attack if another creature is within the attack's range. The attacker must make a DC 18 Wisdom saving throw. On a failed save, the attacker targets the creature that is closest to it, not including itself or Vannifar. If multiple creatures are closest, the attacker chooses which one to target. On a successful save, the attacker is immune to this Instinctive Charm for 24 hours and attacks Vannifar. Creatures that can't be charmed are immune to this effect.