Azgoleth,The True Wyvern

Amphibious: this dragon can breathe air and water

Ice Walk: The Wyvern can move across and climb icy surfaces without needing to make an ability check. additionally, Difficult Terrain composed of ice or snow doesn't cost an extra moment.

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

Cold Breath (Recharge 5-6): The Wyvern exhales an icy blast in a 60-foot cone. each creature in that area must make a DC 19 Constitution saving throw, taking 54 (12d8) cold damage on a failed save, or half as much damage on a successful one.

Frigid Bite: Melee Weapon Attack: +11 to hit, reach 13 ft., one target. Hit: 17 (2d10 + 6) piercing damage plus 4 (1d8) cold damage

Acid Slash: Melee Weapon Attack: +11 to hit, reach 15ft., one target. Hit: 13 (2d6 + 6) slashing damage, plus 18 (2d6 + 4) Acid Damage.

Acid Bomb: there are frozen chunks of acid scattered around the battlefield that when any non draconic creature (which incudes dragonborns,kobolds,wyverns etc.)within 5 ft. activates the bomb., any creature within a 5 ft. radius of it must make a DC 15 Constitution saving throw it deals 20 damage (2d10 + 2) on a failed save or half as much on a successful save.

Detect: The Wyvern makes a Wisdom (Perception) check 

Truesight: 120ft.