Alto Sylph

Dissonance. If the sylph takes damage whilst singing, it's song is disrupted, producing an agonizing discord. The creature that damaged the sylph takes an additional 3 psychic damage from Celestial Song until the beginning of its next turn. If more than one sylph is disrupted, this effect stacks. Damage from Dissonance cannot be reduced in any way save by immunity to psychic damage.

Silence Falls. When the sylph enters an area affected by a Silence spell, or starts its turn there, it is Paralysed until the beginning of its next turn.

Celestial Song. The sylph begins to sing.The sylph can use a bonus action on each of its turns to continue the song.

While the sylph sings, any creature that starts its turn within 300ft of the sylph must make a DC13 Wisdom saving throw, or take 2d4 thunder damage and become frightened until the start of its next turn. On a success, the target takes half as much damage and is not frightened.

Join Chorus. If an allied sylph within 30ft is currently singing, the sylph can instead unite their songs in chorus. For each additional sylph that joins the chorus, (up to a total of five including the original singer), the DC of the Wisdom saving throw increases by 1, and the Celestial Song deals an additional d4 Thunder damage. These effects apply in full to creatures within range of any of the sylphs.

If a sylph is ever more than 30ft from any other member of the chorus, the Joined Chorus ends.

Apocalypsis. The sylph raises its lantern high, spilling roiling light in a 60ft cone. Each creature within the cone must succeed on a DC16 Constitution saving throw or take 3d8 radiant damage, or half as much on a success. Creatures that fail the saving throw cannot become invisible by any means until the end of their next turn.

A chorus of sylphs has one legendary action, which can be used only at the end the turn of a creature not part of the chorus. The chorus regains spent legendary actions on initiative count 20.

If the alto sylph is part of a chorus, and is currently singing, the chorus gains the following legendary action:

Elegy. The melody falls to the alto sylph, which sings a haunting, mournful dirge. Until initiative count 20, any creature affected by the Celestial Song of any member of the chorus has its speed halved until the end of its next turn.