Anivia

Death and Rebirth. When Anivia dies, she explodes in wintery frost. Each creature within 60-feet of it must make a DC 20 Dexterity saving throw, taking 22 (4d10) cold damage on a failed save, or half as much damage on a successful one. The cold freezes any open sources of liquid, like a pond of water, in the affected area.

The explosion destroys Anivia's body and leaves behind an egg-shaped block of ice that weighs 5 pounds. The ice is freezing cold, dealing 21 (6d6) cold damage to any creature that touches it, though no more than once per round. The egg is immune to all damage, and after 1d6 days, it hatches Anivia anew.

Cold Aura.  Any creature that touches Anivia or hits her with a melee attack while within 5 feet of it takes 5 (1d10) cold damage. With a touch, Anivia can also freeze objects that aren’t worn or carried (no action required), trapping it behind a layer of ice.

Flyby. Anivia doesn’t provoke opportunity attacks when she flies out of an enemy’s reach.

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

Siege Monster. Anivia deals double damage to objects and structures.

Glacial Storm (1/day). Anivia summons a blizzard at a point she can see within 120 feet of her. A fierce snowstorm forms in a cylinder 40 ft in diameter and 40 ft tall. Creatures in this space take 8d8 cold damage, or half as much with a successful DC 20 Constitution save. A creature takes this damage if they enter this area for the first time, or end their turn in the area. The area is heavily obscured, but Anivia has awareness of all creatures within the blizzard. 

Multiattack. Anivia makes two attacks: one with her beak and one with its frosty talons, or one with her beak or frosty talons and one with frostbite.

Beak. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 15 (2d6 + 8) fire damage. If the target is a creature or a flammable object, it ignites. Until a creature takes an action to douse the fire, the target takes 5 (1d10) fire damage at the start of each of its turns.

Frosty Talons. Melee Weapon Attack: +13 to hit, reach 15 ft., one target. Hit: 17 (2d8 + 8) cold damage.

Frostbite. Anivia swipes her wing, sending shards of ice flying. Make three ranged attacks. These attacks can be divided amongst three separate targets or at the same creature. These attacks are +13 to hit, dealing 17 (5d6) cold damage on a hit. 

Flash Frost (3/day). Anivia brings her wings together, sending a ball of ice towards a point within 150 ft of her. When the ball reaches this point, it explodes in a 30 ft sphere of harsh winter winds and cold ice shards. Creatures within this area must make a DC 18 Dexterity saving throw or take 35 (10d6) cold damage. Any creatures within 5 ft of the center of the explosion must also make a DC 20 Constitution saving throw or be stunned as their body is shocked by the sudden flash freeze. If a creature is resistant to cold, they have advantage on their save from being stunned

Ice Wall (3/day). Anivia condenses the air into a wall of ice. Choosing a point within 120 ft of herself, Anivia summons a wall of ice 80 ft long, 40 ft tall, and 10 ft. thick. This wall lasts for a minute, or until Anivia dismisses it (no action required), where it melts or evaporates into nothingness. If the wall is summoned beneath a creature, they must make a DC 18 Dexterity saving throw or be lifted by the wall. A creature can choose to fail this saving throw willingly. If the wall is prevented from reaching its full height due to the environment, the creature atop the wall takes 6d6 bludgeoning damage and is restrained. They may use an action on their turn to make a strength or dexterity check (creature's choice) against a DC of 18 to move or fall off the wall. The wall can be divided into 8, 10 ft long, 10 ft thick, 40 ft tall sections. A section of wall has AC 15 and 100 HP, vulnerability to fire, and is immune to cold and poison. If a section of wall is destroyed, the space it occupied is turned into difficult terrain as the ice crumbles to the ground in the area. If it was destroyed with fire, the area is not difficult terrain as the ice melts. Destroying a section of the ice wall does not destroy the entire ice wall, only that section. 

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

Peck. Anivia makes one beak attack.

Move. Anivia moves up to her speed.

Swoop (Costs 2 Actions). Anivia moves up to her speed and attacks with her frosty talons.