Innate Spellcasting.

Hythonia's spellcasting ability is Charisma (spell save DC 18). She can innately cast animate objects once per day requiring no material components.

1/day: animate objects

Legendary Resistance (3/Day).

If Hythonia fails a saving throw, she can choose to succeed instead.

Petrifying Gaze.

When a creature that can see Hythonia's eyes starts its turn within 30 feet of her, Hythonia can force it to make a DC 18 Constitution saving throw if she isn't incapacitated and can see the creature. If the saving throw fails by 5 or more, the creature is instantly petrified. Otherwise, on a failed save the creature 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 Hythonia until the start of its next turn, when it can avert its eyes again. If the creature looks at Hythonia in the meantime, it must immediately make the save. If Hythonia sees herself reflected on a polished surface within 30 feet of her and in an area of bright light, she is affected by her own gaze.

Shed Skin (Mythic Trait; Recharges after a Short or Long Rest).

If Hythonia is reduced to 0 hit points, she doesn't die or fall unconscious. Instead, she sheds her skin, regains 199 hit points, and moves up to her speed without provoking opportunity attacks.

Actions

Multiattack.

Hythonia makes three attacks: one with her claws, one to constrict, and one with her snaky hair.

Claws.

Melee Weapon Attack: +11 to hit, reach 5 ft., one target. Hit: 9 (1d8 + 5) slashing damage plus 4 (1d8) poison damage.

Constrict.

Melee Weapon Attack: +11 to hit, reach 15 ft., one Large or smaller creature. Hit: 16 (2d10 + 5) bludgeoning damage, and the target is grappled (escape DC 19). Until this grapple ends, the target is restrained and takes 15 (3d6 + 5) bludgeoning damage at the start of each of its turns, and Hythonia can't constrict another target.

Snaky Hair.

Melee Weapon Attack: +11 to hit, reach 10 ft., one target. Hit: 31 (4d12 + 5) bludgeoning damage, and Hythonia can pull the target up to 5 feet closer to her if it is a Large or smaller creature.

Legendary Actions

Hythonia 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. Hythonia regains spent legendary actions at the start of its turn.

Move. Hythonia moves up to her speed without provoking opportunity attacks.
Snaky Hair. Hythonia makes one attack with her snaky hair.
Petrified Earth (Costs 2 Actions). Hythonia causes stone spikes to erupt from the ground in a 30-foot radius centered on her. The area becomes difficult terrain until the start of her next turn. Any creature, other than Hythonia, takes 9 (2d8) piercing damage for every 5 feet it moves on those spikes.

Mythic Actions

If Hythonia's mythic trait is active, she can use the options below as legendary actions for 1 hour after using Shed Skin.

Numbing Claws. Hythonia makes two attacks with her claws. If both attacks hit the same creature, it takes an extra 7 (2d6) poison damage and must succeed on a DC 18 Constitution saving throw or become paralyzed until the start of her next turn.
Look at Me (Costs 3 Actions). Hythonia can force a sighted creature she has grappled to see her eyes and be affected by her gaze.

Lair Actions

On initiative count 20 (losing initiative ties), Hythonia can take a lair action to cause one of the following effects. She can't use the same effect two rounds in a row:

Hythonia briefly animates creatures that have been petrified by her gaze. Each statue attacks one creature within 5 feet of it, with a +11 bonus to hit and dealing 10 (3d6) bludgeoning damage on a hit. If a Medium or smaller creature takes this damage, it is also grappled (escape DC 15).
Hythonia causes spectral snakes to erupt from a point she can see within 150 feet of her. Each creature within 20 feet of that point must succeed on a DC 19 Constitution saving throw or take 5 (2d4) piercing damage and become poisoned until the end of its next turn. While poisoned in this way, the creature has disadvantage on Intelligence checks and Intelligence saving throws, and it behaves as if under the effect of the confusion spell.

Regional Effects

The region containing Hythonia's lair is warped by her presence, which creates one or more of the following effects:

A large population of snakes dwells in the region.
Trees within 1 mile of the lair are petrified wood. Plants that stay within 500 feet of the lair for 1 day turn to stone.
Small bodies of water within 1 mile of the lair become poisonous. A creature that drinks the water must succeed on a DC 19 Constitution saving throw or become poisoned for 8 hours. An affected creature can repeat the saving throw at the end of each hour.