Ancient Gold Dragon

The ancient gold dragon can breathe air and water.

3/day. If the ancient gold dragon fails a saving throw, it can choose to succeed instead.

3 legendary actions; one at a time at the end of another creature’s turn, regaining spent uses at the start of its turn

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

Melee Weapon Attack: +17 to hit, reach 15 ft.. Hit: 21 (2d10 + 10) piercing damage.

Melee Weapon Attack: +17 to hit, reach 10 ft.. Hit: 17 (2d6 + 10) slashing damage.

Each creature of the ancient gold dragon's choice that is within 120 ft. 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 ancient gold dragon's Frightful Presence for the next 24 hours.

Melee Weapon Attack: +17 to hit, reach 20 ft.. Hit: 19 (2d8 + 10) bludgeoning damage.

Recharge 5–6. The ancient gold dragon uses one of the following breath weapons.
Fire Breath. The ancient gold dragon exhales fire in a 90-foot cone. Each creature in that area must make a DC 24 Dexterity saving throw, taking 71 (13d10) fire damage on a failed save, or half as much damage on a successful one.
Weakening Breath. The ancient gold dragon exhales gas in a 90-foot cone. Each creature in that area must succeed on a DC 24 Strength saving throw or have disadvantage on Strength-based attack rolls, Strength checks, and Strength saving throws 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.

The ancient gold dragon magically polymorphs into a humanoid or beast that has a challenge rating no higher than its own, or back into its true form. It reverts to its true form if it dies. Any equipment it is wearing or carrying is absorbed or borne by the new form (the ancient gold dragon's choice).
In a new form, the ancient gold dragon retains its alignment, hit points, Hit Dice, ability to speak, proficiencies, Legendary Resistance, lair actions, and Intelligence, Wisdom, and Charisma scores, as well as this action. Its statistics and capabilities are otherwise replaced by those of the new form, except any class features or legendary actions of that form.

The ancient gold dragon makes a tail attack.

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

The ancient gold dragon makes a Wisdom (Perception) check.