Change Shape. Zyphorion can assume the shape of any creature it has seen at will. It can mimic the appearance of a humanoid, beast, or any other form it desires, and can revert to its true form at any time. This transformation lasts indefinitely until Zyphorion chooses to revert to its true form, and it retains its own statistics in any form it assumes.

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

Unusual Nature. Zyphorion doesn’t require sleep and is immune to effects that would put it to sleep.

Chromatic Wrath (Recharge after a Short or Long Rest). Zyphorion can unleash its Chromatic Wrath as a reaction when it is hit by an attack. The attacker takes 44 (8d10) damage of a randomly chosen elemental type (Fire, Lightning, Acid, Poison, or Cold).

Innate Magic. Zyphorion has resistance to magic and can cast the following spells at will (without expending spell slots): Dispel Magic, Counterspell, Teleport, Wall of Fire, Chain Lightning.

Elemental Mastery. Zyphorion’s attacks deal an additional 22 (5d8) damage of a randomly determined elemental type (Fire, Lightning, Acid, Poison, or Cold).

Magic Resistance. Zyphorion has advantage on saving throws against spells and other magical effects.

Multiattack. Zyphorion makes three attacks: one with its bite, one with its claws, and one with its tail.

Bite. Melee Weapon Attack: +19 to hit, reach 15 ft., one target. Hit: 45 (6d10 + 10) piercing damage plus 22 (5d8) elemental damage (randomly determined between Fire, Lightning, Acid, Poison, or Cold).

Claw. Melee Weapon Attack: +19 to hit, reach 10 ft., one target. Hit: 35 (4d8 + 10) slashing damage plus 22 (5d8) elemental damage (randomly determined between Fire, Lightning, Acid, Poison, or Cold).

Tail. Melee Weapon Attack: +19 to hit, reach 20 ft., one target. Hit: 40 (5d8 + 10) bludgeoning damage plus 22 (5d8) elemental damage (randomly determined between Fire, Lightning, Acid, Poison, or Cold).

Breath Weapon (Recharge 5–6). Zyphorion exhales destructive energy in a 120-foot cone. Each creature in that area must make a DC 26 Dexterity saving throw, taking 120 (16d10) damage of a randomly chosen elemental type (Fire, Lightning, Acid, Poison, or Cold) on a failed save, or half as much on a successful one.

Cataclysmic Breath (Recharge 6). Zyphorion exhales its full elemental fury, targeting one creature within 150 feet. The target must succeed on a DC 28 Constitution saving throw or take 150 (30d10) damage, divided between Fire, Lightning, Acid, Poison, and Cold. On a successful save, it takes half damage.

Empowered Breath (Recharge 5–6). Zyphorion can focus its elemental power to enhance its Breath Weapon. It deals an additional 22 (5d8) damage of a randomly selected elemental type with its next Breath Weapon.

Chromatic Shield (Recharge 5–6). When Zyphorion is hit by an attack, it can use its reaction to raise a shield of elemental energy. The attacker must make a DC 26 Constitution saving throw or take 44 (8d10) damage of a randomly chosen elemental type (Fire, Lightning, Acid, Poison, or Cold). On a successful save, the attacker takes half damage.

Zyphorion can take 5 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. Zyphorion regains spent legendary actions at the start of its turn.

Tail Sweep (Costs 1 Actions). Zyphorion makes a tail attack.

Elemental Pulse (Costs 1 Actions). Zyphorion deals 22 (5d8) elemental damage (randomly chosen from Fire, Lightning, Acid, Poison, or Cold) to one target within 60 feet.

Wing Buffet (Costs 2 Actions). Zyphorion beats its wings, forcing creatures within 30 feet of it to make a DC 26 Strength saving throw or be knocked prone and pushed 15 feet away.

When Zyphorion drops to 0 hit points, it can use its mythic actions to return to full health and gain a new set of abilities for the remainder of the encounter.

Wrathful Rebirth. Zyphorion returns to life with full hit points and gains a new legendary action.

Elemental Cataclysm. Zyphorion unleashes a devastating elemental attack, causing the area around it to erupt in chaos. All creatures within 60 feet must make a DC 28 Dexterity saving throw, taking 180 (24d10) damage of a randomly chosen elemental type.