Armor Class 19 (natural armor)
Hit Points 136 (16d6 + 80)
Speed fly 30 ft.
Saving Throws CON +9, WIS +12
Skills Deception +13, Insight +12, Intimidation +13, Perception +16
Damage Immunities cold, poison
Condition Immunities charmed, exhaustion, frightened, paralyzed, petrified, poisoned, prone, stunned
Senses blindsight 120 ft. (blind beyond this radius), truesight 120 ft., passive Perception 26
Languages all, telepathy 1,000 ft.
Challenge 11
Divine Being. Auril can't be surprised and can't be changed into another form against her will.
Divine Resurrection. When Auril drops to 0 hit points, her crystalline form shatters and her divine spark vanishes. She is dead until the next winter solstice, when she reappears at full health in a cold, remote location of her choosing.
Frigid Aura. So long as Auril has at least 1 hit point in this form, each creature within 10 feet of her takes 10 cold damage at the start of each of her turns.
Legendary Resistance (1/Day in This Form). If Auril fails a saving throw, she can choose to succeed instead.
Magic Resistance. Auril has advantage on saving throws against spells and other magical effects.
Unusual Nature. Auril doesn't require air, food, drink, or sleep.
Multiattack. Auril uses Polar Ray twice.
Polar Ray. Ranged Spell Attack: +13 to hit, range 120 ft., one target. Hit: 14 (4d6) cold damage.
Blizzard Veil. Auril creates a magical blizzard in a 30-foot-radius sphere centered on herself. The area within the sphere is heavily obscured, and the sphere moves with Auril. The effect lasts until Auril drops to 0 hit points in this form, until she chooses to end the effect (no action required), or until her concentration is broken (as if concentrating on a spell).
Polar Ray. Auril uses Polar Ray.
Intensify Aura (Costs 2 Actions). Auril's Frigid Aura deals an extra 10 cold damage until the end of her next turn.
Blinding Gleam (Costs 2 Actions). Auril's form flares with a blue light. Each creature that can see Auril and is within 10 feet of her must succeed on a DC 17 Wisdom saving throw or be blinded by Auril's magical gleam for 1 minute. The blinded creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.
IDRotF, p. 278