As you spend 1 minute to cast this spell, a wall of water springs into existence at a point within sight range. You can make the wall up to 90 meters long, 90 meters high, and 18 meters thick. The wall lasts for the duration.
When the wall appears, each creature within its area must make a Reflex saving throw.
On a failed save, a creature takes 6d6 bludgeoning damage, or half as much damage on a successful save. Additionally, any burning creature in the area stops burning.
At the start of each of your turns after the wall appears, the wall’s height is reduced by 18 meters and the wall, along with any creatures in it, moves 18 meters away from you. Any Huge or smaller creature inside the wall or whose space the wall enters when it moves must succeed on a Reflex saving throw or take 5d6 bludgeoning damage. A creature can take this damage only once per round. The damage creatures take from the spell on subsequent rounds is reduced by 1d6. When the wall reaches 0 meters in height, the spell ends.
A creature caught in the wall can move by swimming. Because of the force of the wave, though, the creature must make a successful Brawn check against your spell save DC in order to move at all. If it fails the check, it can’t move. A creature that moves out of the area falls to the ground.