Ballad of Seronious the Sick

A small scroll of what seems to be a pamphlet of songs. Curiously the notes have small symbols imprinted on the parchment next to them I wonder what would happen if these notes where sung aloud.

As an action, you can recite the lyrics of the ballad. Everyone within a 15ft radius must make a DC 13 Constitution saving throw. On a failure they take 1d6+3 poison damage and must spend and action vomiting on their next turn. On a success targets take half damage and are immune to the effect for the next 24 hours