Burst Stone

You cause the ground at a point you can see within range to explode. The ground must be sand, earth, or unworked rock. Each creature within 10 feet of that point must make a Dexterity saving throw. On a failed save, the creature takes 4d8 bludgeoning damage and is knocked prone. On a successful save, the creature takes half as much damage and isn't knocked prone. The area then becomes difficult terrain with a 5-foot-deep pit centered on the point you chose.