Ancient Greater Valyrian Dragon

Legendary Resistance (6/Day). If the dragon fails a saving throw, it can choose to succeed instead.  

Innate Spellcasting (4/Day). The dragon can innately cast earth tremor, requiring no material components. Its innate spellcasting ability is Wisdom.

Multiattack. The dragon makes one bite attack, one attack with its talons, and one with its tail.

Bite. Melee Weapon Attack: +14 to hit, reach 15 ft., one target. Hit: 64 (6d10+8) piercing damage and 29 (4d6+8) fire damage.

Talons. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 68 (8d8+8) slashing damage.

Stomp. Melee Weapon Attack: +13 to hit, reach 5 ft., one target. Hit: 65 (10d6+8) bludgeoning damage.

Tail. Melee Weapon Attack: +14 to hit, reach 25 ft., one target. Hit: 73 (6d8+8) bludgeoning damage and the target must succeed on a DC 21 Strength saving throw or be knocked prone.

Wing Attack (Recharge 4-6). The dragon beats its wings. Each creature within 15 feet of the dragon must succeed on a DC 20 Dexterity saving throw or take 28 (4d6+8) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.

Frightful Presence. Each creature of the dragon's choice that is within 140 feet of the dragon and aware of it must succeed on a DC 19 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.

Fire Breath (Recharge 5-6). The dragon exhales bright yellow-orange flames in a 90-foot cone. All creatures in that radius must make a DC 23 Dexterity saving throw, taking 81 (14d6) fire damage on a failed save, or half as much on a success.

The dragon can take 4 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 Perception (Wisdom) check.

Melee Strike. The dragon makes a melee attack. If the attack hits, it deals 2 extra damage of the attack's main damage.

Harsh Tremor. The dragon casts earth tremor once or twice.

Flameball. The dragon unleashes a enormous fireball on to a single target. The target must make a DC 17 Dexterity saving throw, taking 118 (15d8) fire damage on a failed save, or half as much on a success.

Ferocious Roar (Costs 2 Actions). The dragon lets out a powerful, somewhat guttural, roar. All creatures that are hostile to the dragon and its allies that are 55 feet or less away the dragon that can hear it must succeed on a DC 18 Wisdom saving throw or be frightened of the dragon for the next 2 rounds. All creatures that are allies to the dragon that are 55 feet or less away from the dragon that can hear it have advantage on attack rolls for the next 2 rounds.