Earthshatter

As an action, you slam a blunted weapon or object into the ground. A split second later, the earth gives in and shatters and quakes - causing all creatures within range to make a Dexterity saving throw, suffering 2d8 Bludgeoning damage and knocking it prone. The caster does not need to make a save and will not take damage. Succeeding the saving throw causes only half damage and the creature(s) are not knocked prone. The shattered earth that remains counts as difficult terrain. 

At Higher Levels. Increases the range by 5 feet and the damage dice by 1d6 for each spell slot used above 1st level.