Eruption

You conjure up a wave of lava that crashes down on an area within range. The area can be up to 30 feet long, up to 10 feet wide, and up to 10 feet tall. Each creature in that area must make a Dexterity saving throw. On a failure, a creature takes 2d8 bludgeoning and 4d8 fire damage and is knocked prone. On a success, a creature takes half as much damage and isn't knocked prone. The lava then spreads out across the ground in all directions, igniting flammable objects in its area and within 30 feet of it. A creature that stays in the lava takes 1d12 fire damage each turn it is in contact. The lava counts as rough terrain. (An equivalent amount of water, such as from the Tidal Wave spell, a Decanter of Endless Water, or a portal to the Elemental Plane of Water can cool the lava in one round turning the area into rough terrain and restraining those still in the area where the lava cooled.