Earth Shatter

You swing your weapon directly down onto the ground in front of you with such force that it shatters the earth in a 15ft cube.

Each creature in the 15ft cube must make a DEX save, on a failure they are knocked prone and take 2D8 force damage. On a success, creatures take half damage and are not knocked prone.

Each square in the cube becomes difficult terrain and the earth itself shatters underfoot.