Boulder smash

A bright beige light will channel around the small pebble being held by the caster. After a brief delay the pebble will shoot itself toward an area chosen by its caster. While in the air the pebble will spin rapidly, growing in size till it becomes a massive boulder. Upon impact, the boulder explodes into multiple tinier rocks traveling  at incredible speeds in all directions. At this point, each creature in a 10 foot radius must make a dexterity saving throw. A target takes 6D8 earth damage on a failed save or half as much on a successful one.

The impacted area will be turned into a 5 foot deep crater filled with jagged rocks, turning it into difficult terrain