Arther fist (For custom campaign.)

You make a fist and at a point you choose a phantom fist appears above them. Then it crashes down upon everyone in a 10 diameter. All creatures must make a wisdom saving throw. In a sucses it passes through them, and on a fail they take 5d6 Blugeting damage and get knocked prone.

Casting this with a higher level spell slot will make it increase 1d6 every level above 3rd.