Baba Yaga

Cronesight. Baba Yaga has advantage on Wisdom (Perception) checks that rely on sight.

Cronespeech. Baba Yaga has advantage on Charisma checks against creatures with an Intelligence of 6 or lower.

Sylvan Strikes. Baba Yaga's pestle and bite attacks are magical.

Mortar and Pestle. Baba Yaga flies in a Large mortar and pestle, which is immune to damage and can’t be the target of spells or effects. It provides Baba Yaga partial cover from ranged attacks. While in the mortar and pestle, Baba Yaga doesn’t provoke an opportunity attack when she flies out of an enemy’s reach. If Baba Yaga is knocked prone, stunned, or incapacitated while flying in the mortar, it will gently set her on the ground and disappear for 1 hour. The pestle remains with her.

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

Spellcasting.Baba Yaga is a 17th-level spellcaster. Her spellcasting ability is Wisdom (spell save DC 20, +12 to hit with spell attacks). Baba Yaga has following spells prepared:
Cantrips (at will): create bonfire, chill touch, infestation
1st level (4 slots): bane, grease
2nd level (3 slots): enthrall, misty step
3rd level (3 slots): bestow curse, stinking cloud
4th level (3 slots): confusion
5th level (2 slots): modify memory
6th level (1 slot): irresistible dance
7th level (1 slot): plane shift
8th level (1 slot): feeblemind
9th level (1 slot): true polymorph

Multiattack. Baba Yaga makes two pestle attacks and one bite attack, or three pestle attacks.

Pestle. Melee Weapon Attack: +10 to hit, reach 10 ft., one target. Hit: 15 (2d10 + 4) bludgeoning damage. 

Bite. Melee Weapon Attack: +10 to hit, reach 5 ft., one target. Hit: 25 (6d6 + 4) [damage type] damage. While in her mortar and pestle, Baba Yaga cannot make a bite attack against a Small or smaller creature.

Breath of the Bone Mother (Recharge 5-6). Baba Yaga exhales a 40-foot cone of putrid air that smells like rotten meat. Creatures caught in the area must succeed on a DC 18 Constitution saving throw or take 18 (4d8) poison damage and 18 (4d8) necrotic damage. On a successful save, a creature takes half as much damage.

Dance of the Time Taunter (1/day). When Baba Yaga’s turn ends, she can take an additional turn. A creature able to see Baba Yaga dance through time has its understanding of the universe challenged and must succeed on a DC 18 Intelligence saving throw or be stunned until the end of its next turn. A set of iron dentures flap through the air, screeching in a voice like metal scraping on metal.

Baba Yaga can take 3 legendary actions, choosing from the options below. Only one legendary action can be used at a time and only at the end of another creature’s turn. She regains spent legendary action at the start of her turn.

Cantrip. Baba Yaga casts a cantrip.

Pestle. Baba Yaga makes one pestle attack.

Mortar. Baba Yaga mounts or dismounts her mortar, or moves up to half her speed if in the mortar.