Bonefiddle

You conjure a spectral fiddle or other musical instrument in the air above the targeted creature. The instrument descends into the target's body and begins to play against its skeleton. At the start of each of its turns, the affected creature must make a Constitution saving throw. On a failed save, the creature takes 4d6 points of thunder damage and has disadvantage on all Stealth checks. On a successful save, the creature takes half damage and doesn't have disadvantage. This spell doesn't affect creatures that don't have bones or an exoskeleton, such as plants or oozes.

At the end of each of its subsequent turns, a target that fails its initial saving throw can make another Constitution saving throw. On a success, the spell ends. On a failure, the target takes an additional 4d4 necrotic damage and continues to have disadvantage on Stealth checks.

The spell's effects continue even if the target moves from your line of sight, so long as you can hear it.

At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, the damage increases by 1d6 for each slot level above 4th.