Tidal Surge

You conjure up a wave of water that crashes down on an area within range. The area can be up to 30 ft long, up to 10 ft wide, and up to 10 ft tall.

• Each creature in that area must make a Dexterity saving throw.
• On a failed save, a creature takes 4d8 Cold damage, applying Wet and is knocked prone.
• On a successful save, a creature takes half as much damage and isn’t knocked prone.
• The water then spreads out across the ground in all directions, extinguishing unprotected flames in its area and within 30 ft of it, blanketing the surface in standing water. 

Using a Higher-Level Spell Slot. The damage increases by 1d8 for each spell slot level above 3.