A spherical boulder of elemental earth rolls around the battlefield under your control. It moves up to 20 feet in a straight line every round (less if it strikes an immovable object) in a direction of your choice, bowling over creatures in its path. Creatures struck by the boulder must make a successful save or be knocked prone, taking 3d6 points of bludgeoning damage as the boulder rolls over them.

The boulder has hardness 5 and 150 hit points.