Conjure condensed Acid Tsunami

You conjure up a wave of Acidic slime that crashes down on an area within range. The area can be up to 320 feet long, up to 320 feet wide, and up to 320 feet tall but can be much smaller depending on casters will. Each creature in that area must make a Dexterity saving throw. On a failed save, a creature takes 11d8 acid damage and is knocked prone. On a successful save, a creature takes half as much damage and is still knocked prone  prone. The water then spreads out across the ground in all directions, extinguishing unprotected flames in its area and within 320 feet of it, and then it vanishes.