Dragon's Melody - Weapon Enchantment

Upon triggering this enchantment, the bearer must begin playing the enchanted musical instrument. The song played builds up and ultimately releases the Dragon's Breath spell, whose damage type is determined by the specific song played (as agreed upon by the DM). The enchantment builds to greater strength the longer the triggering song is played without interruption, starting at 3d6 and increasing by 1d6 per action spent to play the song, to a maximum of 10d6. Each action spent to empower the enchantment's spell must sacrifice a spell slot (any level) or the spell's power is not increased. The enchantment's spell power is increased only if the caster does not fail any performance checks to maintain the spell until the start of their next turn.

If the triggering player takes damage while playing the enchantment's triggering song, the song-player must immediately succeed on a performance check or the enchantment fails, releasing immediately as if cast at the last successfully empowered level. The DC for the performance check is equal to 10 or half the damage received, whichever is higher. Upon failure, the enchantment immediately releases at the spell level that was last successfully empowered or the base 3d6 level if the enchantment was not empowered further. 

Upon release, any creature hit by the spell's effect must make a DC 12 dexterity saving throw, taking half damage on a success or full damage on a failure.