Amphibious. The song dragon can breathe air and water.

Euphonic Resistance. If the song dragon is subjected to an effect the would silence it, it can choose to be affected for 1 round only, regardless of the effect's duration.

Innate Spellcasting. The song dragon's innate spellcasting ability is Charisma (spell save DC 16). It can innately cast the following spells, requiring no material components:

At will: Minor illusion, Mage hand (to create musical notes and tones)

3/day each: cure wounds (2nd level), Charm Person

1/day each: counter spell, greater invisibility 

Multiattack. The dragon makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 5 (1d6 + 2) piercing damage 

Claw. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 4 (1d6 + 2) slashing damage.

Song of Serenity (3/Day). The song dragon sings a calming and entrancing melody. Each creature of the dragon’s choice within 60 feet of the dragon must succeed on a DC 16 Wisdom saving throw or be charmed for 1 minute. While charmed in this way, the creature is incapacitated and has a speed of 0. The effect ends for a creature if it takes damage or if another creature uses an action to shake it out of its stupor.

Sonic Breath . The song dragon exhales a blast of sonic energy in a 30-foot cone. Each creature in that area must make a DC 15 Constitution saving throw, taking 35 (10d6) thunder damage on a failed save, or half as much damage on a successful one. This breath silences creatures for 1 minute on a failed save. A creature can repeat the saving throw at the end of each of its turns, ending the silenced effect on itself on a success.