Amphibious. The dragon can breathe air and water.

Legendary Resistance(1). Can turn any fail save into a succes 

Frightful Presence. any creature that starts its turn within 15 of the Dragon must make a Wisdom 15 Save or be frighten. The Creature can repeat this save at the start of their next turn. Creature that pass this effect are immune for 72 hours. 

Multiattack. The dragon makes two attacks: with either its claws Or Bite.

Bite. Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 8 (3d4+2) piercing damage plus 13 (3d6+4) acid damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage. The Creature Must make a Str Save Dc 13 or Be Grappled/Knocked Prone.

Tail. From a 15ft semi circle centering at the behind the Dragon. any creature with must make a Dc15 or take. 4d6+4 Bludgeon damage & be Push back 15 ft. Staying & taking halve on a success

Acid Breath (Recharge 5–6). The dragon exhales acid in a 30­-foot line that is 5 feet wide. Each creature in that line must make a DC 15 Dexterity saving throw, taking 36 (8d6) acid damage on a failed save, & lose -3 to ac to any non magical equipment. or -1 ac & half as much damage on a successful one.

Tar Breath (Recharge 5–6). The Dragon Expunges a blast within 120ft of it choosing. Center on that point a 15ft Radius of Tar lands. Any creature within that space must make  Con Save Dc15 or be restrained. Taking 20 10d4 Acid damage. Taking half on a Success. At the start of thier turn a creature Restrained takes 5d4 acid damage & can attempt to break free. trying again with thier action if failed.

Bloodied Burns.When the Dragon reaches 1/2 of its Hp. It Can immediately use its Wing Attack as with the disengage action. Furhter more it gain an additional use of its Legendary Resistance & breath charge. However its breath attack must Not be the one it had used last.   

This Creature has Two Legendary actions.

Wing Attack. all creature with 5ft of the dragon must make Str Save 13. Or take 2d6+4 bludgeon & fall prone. Taking only the half on the success. the Dragon then uses its movement to fly.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 11 (2d6 + 4) slashing damage. The Creature Must make a Str Save Dc 13 or Be Grappled/Knocked Prone.

Tail. From a 15ft semi circle centering at the behind the Dragon. any creature with must make a Dc15 or take. 4d6+4 Bludgeon damage & be Push back 15 ft. Staying & taking halve on a success