Legendary Resistance (5/Day). If Adria fails a saving throw, she can choose to succeed instead.

Spellcasting. Adria is an 20th-level spellcaster. Its spellcasting ability is Wisdom (spell save DC 22, +14 to hit with spell attacks). Adria has the following spells prepared:

Cantrips (at will): mage hand, prestidigitation, ray of frost

1st level (4 slots): detect magic, magic missile, shield, thunderwave

2nd level (3 slots): acid arrow, detect thoughts, invisibility, mirror image

3rd level (3 slots): animate dead, counterspell, dispel magic, fireball

4th level (3 slots): banishment, death ward

5th level (3 slots): dawn, scrying

6th level (2 slot): disintegrate, globe of invulnerability

7th level (2 slot): crown of stars, plane shift

8th level (1 slot): demiplane, maddening darkness, dark star

9th level (1 slot): imprisonment time ravage

Shed Skin (Mythic Trait; Recharges after a Short or Long Rest). If Adria 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. She loses her sword and fights with her claws instead. 

Multiattack. Adria makes three attacks.

Claw (Mythic Form Only). Melee Weapon Attack: +12 to hit, reach 5 ft., one target. Hit: 17 (2d8 + 7) piercing damage.

Binding Blade (Standard Form Only). Ranged Spell Attack: +12 to hit, range 120 ft., one target. Hit: 28 (6d6 + 8) force damage, and if the target is a creature, it must succeed on a DC 21 Strength saving throw or be restrained until the end of its next turn.

Adria 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. Adria regains spent legendary actions at the start of her turn.

Attack. Adria makes one attack.

Fey Step. Adria teleports to an unoccupied space she can see within 30 feet of her.

Frightening Gaze (Costs 2 Actions). Adria fixes her gaze on one creature it can see within 10 feet of it. The target must succeed on a DC 22 Wisdom saving throw against this magic or become frightened for 1 minute. The frightened target can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a target's saving throw is successful or the effect ends for it, the target is immune to Adria's gaze for the next 24 hours.

Awaken Grove Guardians (Costs 3 Actions). Adria animates one or two trees she can see within 120 feet of her, causing them to uproot themselves and become awakened trees (see the Monster Manual for their stat blocks) for 1 minute or until Adria uses a bonus action to end the effect. These trees understand Druidic and obey Adria's spoken commands, but can’t speak. If she issues no commands to them, the trees do nothing but follow her and take the Dodge action.

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

Numbing Claws. Adria makes two attacks with her claws. If both attacks hit the same creature, it takes an extra 21 (6d6) 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). Adria can force a sighted creature she has restrained to see her eyes and be affected by her gaze, even if they previously succeeded. The chosen creature can only be affected by this ability once per day.