Ancient brown dragon

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

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

Bite. Melee Weapon Attack: +16 to hit, reach 15 ft., 1 target. Hit: 20 (2d10 + 9) piercing damage plus 7 (2d6) fire damage. 

Claw. Melee Weapon Attack: +16 to hit, reach 10 ft., 1 target. Hit: 16 (2d6 + 9) slashing damage. 

Tail. Melee Weapon Attack: +16 to hit, reach 20 ft., 1 target. Hit: 18 (2d8 + 9) bludgeoning damage. 

Frightful Presence. Each creature of the dragon’s choice that is within 120 ft. of the dragon and aware of it must succeed on a DC 20 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.

Sand Breath (Recharge 5-6). The brown dragon exhales a spray of hot sand in a 90ft cone. Each creature within the radius must make a DC 23 Constitution saving throw or take 82 (15d10) fire damage and the creature is blinded for 1 minute, they can repeat the saving throw at the end of each turn to rid themselves of the blindness. On a successful saving throw a creature takes half damage. 

The ancient brown 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 ancient brown 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 ft. of the dragon must succeed on a DC 24 Dexterity saving throw or take 16 (2d6 + 9) bludgeoning damage and be knocked prone and blinded for 1 round. The dragon can then fly up to half its flying speed.