Argynvost's Shade

Legendary Resistance (3/Day). If the dragon fails a saving throw, it can choose to succeed instead.

Undead Nature. Argynvost doesn't require air, food, drink, or sleep.

Horrifying Visage. Any creature that starts its turn within 30 feet of Argynvost and can see him must make a DC 14 Wisdom saving throw or become frightened for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success. If a creature's saving throw is successful or the effect ends for it, the creature is immune to Horrifying Visage for the next 24 hours.

Undead Fortitude. If damage reduces Argynvost to 0 hit points, he must make a Constitution saving throw with a DC of 5 + half the damage taken, unless the damage is radiant or from a critical hit. On a success, Argynvost drops to 1 hit point instead.

Multiattack. The dragon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +13 to hit, reach 10 ft., one target. Hit: 19 (2d10 + 8) piercing damage.

Claw. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 15 (2d6 + 8) slashing damage.

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

Breath Weapons (Recharge 5–6). The dragon uses one of the following breath weapons.

Icy Death. The dragon exhales a blast of icy rot in a 60-foot cone. Each creature in that area must make a DC 20 Constitution saving throw, taking 58 (10d8) cold damage plus 58 (10d8) necrotic damage on a failed save, or half as much damage on a successful one.

Paralyzing Breath. The dragon exhales paralyzing gas in a 60-foot cone. Each creature in that area must succeed on a DC 20 Constitution saving throw or be paralyzed for 1 minute. A creature can repeat the saving throw at the end of each of its turns, ending the effect on itself on a success.

Argynvost 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. Argynvost regains spent legendary actions at the start of his turn.

Claw. Argynvost makes one Claw attack.

Treacherous Ice. Magical ice covers the ground in a 20-foot radius centered on a point the dragon can see within 120 feet of itself. The ice, which is difficult terrain for all creatures except Argynvost, lasts for 10 minutes or until the dragon uses this legendary action again.

Black Flame Retreat (Costs 2 Actions). Argynvost becomes an inky cloud of flames and can move up to half his flying speed without provoking opportunity attacks, then resumes his true form. During this movement, he can move through creatures and objects as if they were difficult terrain. If he moves through a creature, it must succeed on a DC 21 Constitution saving throw or be blinded until the end of its next turn. If Argynvost ends this move inside an object, he takes 5 (1d10) force damage and is shunted to the nearest unoccupied space.