As two actions, you create a wave of water that crashes down at a point within 20 meters. Each creature in a sphere centered on that point must make a Reflex saving throw.
On a failure, it takes 3d8 bludgeoning damage, is wet until the end of its next turn, is knocked prone if it is Large or smaller, and is pushed 3 meters away from the center of the sphere if it is Large or smaller.
On a critical failure, it takes twice as much damage and is pushed 6 meters away from the center of the sphere if it is Large or smaller.
On a success, it takes half as much damage.
On a critical success, it takes no damage.
The water then spreads out across the ground in all directions, causing all creatures and objects in the area to become wet until the end of their next turn.
You can increase the damage by 1d8, push each creature an additional meter, and affect a creature of a larger size for each additional mana expended.