Chaos Dragon

Amphibious. The dragon can breathe air and water.

Ice Walk. The dragon can move across and climb icy surfaces without needing to make an ability check. Additionally, difficult terrain composed of ice or snow doesn't cost it extra movement.

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

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

Multiattack. The dragon can use its Frightful Presence. It then makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +17 to hit, reach 15 ft., one target. Hit: 21 (3d10 + 10) piercing damage.

Claw. Melee Weapon Attack: +17 to hit, reach 10 ft., one target. Hit: 17 (3d6 + 10) slashing damage.

Tail. Melee Weapon Attack: +17 to hit, reach 20 ft., one target. Hit: 19 (3d8 + 10) bludgeoning damage.

Frightful Presence. Each creature of the dragon's choice that is within 120 feet of the dragon and aware of it must succeed on a DC 24 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 the dragon's Frightful Presence for the next 24 hours.

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

Acid Breath. The dragon exhales acid in a 90--foot line that is 10 feet wide. Each creature in that area must make a DC 22 Dexterity saving throw, taking 67 (15d8) acid damage on a failed save, or half as much damage on a successful one.

Lightning Breath. The dragon exhales lightning in a 120--foot line that is 10 feet wide. Each creature in that area must make a DC 23 Dexterity saving throw, taking 88 (16d10) lightning damage on a failed save, or half as much damage on a successful one.

Poison Breath. The dragon exhales poisonous gas in a 90--foot cone. Each creature in that area must make a DC 22 Constitution saving throw, taking 77 (22d6) poison damage on a failed save, or half as much damage on a successful one.

Fire Breath. The dragon exhales fire in a 90--foot cone. Each creature in that area must make a DC 24 Dexterity saving throw, taking 91 (26d6) fire damage on a failed save, or half as much damage on a successful one.

Cold Breath. The dragon exhales an icy blast in a 90--foot cone. Each creature in that area must make a DC 22 Constitution saving throw, taking 72 (16d8) cold damage on a failed save, or half as much damage on a successful one.

Charming Breath. The dragon exhales gas in a 90--foot cone. Each creature in that area must succeed on a DC 22 Wisdom saving throw or become charmed for 1 minute.

The dragon 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. The dragon regains spent legendary actions at the start of its turn.

Detect. The dragon makes a Wisdom (Perception) check.

Tail Attack. The dragon makes a tail attack.

Wing Attack (Costs 2 Actions). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 25 Dexterity saving throw or take 17 (3d6 + 10) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.