Thunder Down Under

A creature you can see of your choice within range must succeed a Constitution saving throw or release a fart so flatulent it takes damage. The explosive force of the fart deals 3d6 thunder damage to the target and an additional 1d6 thunder damage to all creatures and objects within a 15-foot cone behind the target. If the target succeeds it talks 3d6 thunder damage halved and does not expend a fart. This spell has no effect if the target is incapable of releasing flatulence, such as a construct.