Adult Onyx Dragon

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

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

Bite. Melee Weapon Attack +11 to hit, reach 10ft., one target. Hit: 17 (2d10+6) piercing damage. plus 4 (21d8) bludgeoning.

Claw. Melee Weapon Attack +7 to hit, reach 5ft., one tatget. Hit: 13 (2d6+6) slashing damage.

Tail. Melee Weapon Attack: +11 to hit, reach 15 ft., one target. Hit: 15 (2D8+6) Bludgeoning damage.

Frightful Presence. Each creature of the dragon's choice that is within 120 feet pf the dragon and aware of it must succeed on a DC 15 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 endeds for it, the creature is immune to the dragon's frightful presence for 24 hours.

Rock Breath (Recharge 5-6). The drragon exhales rocks in a 60-foot line that is 5 feet wide. Each creature in that line must make a DC 18 Dexterity saving throw, taking 54 (12d8) bludgeoning damage on a failed save, of half as much damage on a successful one.

The dragon can take 3 legendary actions, choosing from the opions below. Only one legendary action opions can be used at a time and only at the end of another creature's turn. The dragon regains spent legendery action at the start of its turn.

Detect (Costs 1 Actions). The dragon makes a Wisdom (Perception) check.

Tail Attack (Costs 1 Actions). 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 19 Dexterity saving throw or take 13 (2d6+6) bludgeoning damage and be knocked prone. The dragon can then fly up half its flying speed.