Erupting Volcano

You create a miniature volcano that erupts in a location you choose within range. The volcano forms a 10-foot radius, 20-foot-high cylinder. When it appears, each creature in that area must make a Dexterity saving throw. On a failed save, a creature takes 5d6 fire damage and is knocked prone. On a successful save, the creature takes half as much damage and isn't knocked prone.

At the start of each of your turns for the duration, the volcano spews molten rock in a 30-foot cone. Each creature in that cone must make a Dexterity saving throw. On a failed save, a creature takes 3d6 fire damage and is set on fire, taking 1d6 fire damage at the start of its turn until it uses an action to extinguish the flames. On a successful save, the creature takes half as much damage and isn't set on fire.

At Higher Levels: When you cast this spell using a spell slot of 5th level or higher, the initial damage increases by 1d6 for each slot level above 4th.