As two actions, the ground in a sphere centered on a point within 20 meters twists and becomes doughlike with hundreds of little teeth. The area becomes difficult terrain for the duration. When a creature moves into or within the area, it takes 2d4 piercing damage for every meter it travels.
As an action, you can cause the maws to move up to 2 meters.
You can increase the damage by 1d4 for every two additional mana expended.