Adult Rockhide Dragon

Minor Immutability. The dragon has advantage on saving throws against its form being changed in any way.

Lesser Legendary Resistance (2/Day). If the dragon fails a saving throw, it can choose to reroll with advantage.

Multiattack. The dragon makes three attacks: one with its bite and two with its claws. It can replace the claw attacks with Fireball attacks.

Bite. Melee Weapon Attack: +9 to hit, reach 10 ft., one target. Hit: 14 (2d8 + 5) piercing damage plus 2 (1d4) fire damage.

Claw. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 10 (1d10 + 5) slashing damage.

Tail. Melee Weapon Attack: +9 to hit, reach 15 ft., one target. Hit: 12 (2d6 + 5) bludgeoning damage.

Fireball. Melee Weapon Attack: +5 to hit, range 100 ft., one target. Hit: 9 (2d8) fire damage plus 3 (1d6) bludgeoning damage.

Fire Breath (Recharge 6). The dragon exhales a blast of fire in a 50-foot cone. Each creature in that area must make a DC 16 Constitution saving throw, taking 32 (13d4) fire damage on a failed save, or half as much damage on a successful one.

Havoc (Recharge 6). The dragon unleashes hidden arcane energies deep within it that makes it that for the next 4 rounds, whenever the dragon hits a creature with an attack, the dragon must make a DC 12 Strength saving throw. On a failure, the dragon automatically takes 2 force damage and is stunned until 1 round has passed or until it takes damage or something comes to shake it awake before 1 round has passed. On a success, the dragon has advantage on all attack rolls and Strength and Constitution saving throws until the end of the spell duration. If the dragon succeeds on two of these saving throws in a row, all of its attacks deal an extra two die of damage and it has advantage on all attack rolls and Strength and Constitution saving throws until the end of the duration.

The dragon can take 2 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 10 feet of the dragon must succeed on a DC 15 Dexterity saving throw or take 12 (2d6 + 5) bludgeoning damage and be knocked prone. The dragon can then fly up to half its flying speed.