Cantus Distractum

Play your instrument or sing in a purposefully distracting fashion. All creatures within 30 feet of you must succeed on a constitution saving throw or take 2d6 thunder damage (taking half damage on a successful save). Any creature within range may spend a reaction to begin to sing/scream along, adding 1d6 to the damage of this spell for each additional creature joining in. If a creature has proficiency in a musical instrument, it can choose to add 2d6 damage instead of 1d6.
Any creature within range who is currently concentrating on a spell must make a concentration saving throw. The DC for the save is 12 or 3/4 the damage taken from the spell (rather than the usual 10 or ½).
When cast at higher levels: Add 1d6 of starting damage for each level above 2nd. This extra damage die does not apply to creatures joining in.