Crushing Haymaker A5E

Your fist reverberates with destructive energy, and woe betide whatever it strikes. As part of casting the spell, make a melee spell attack against a creature or object within 5 feet. If you hit, the target of your attack takes 7d6 thunder damage, and must make a Constitution saving throw or be knocked prone and stunned until the end of its next turn. This spell's damage is doubled against objects and structures.

The spell deals an extra 1d6 of thunder damage for each slot level above 3rd.