The Grimoire is operated by DiceBard.com, Dice Bard has everything you need to play 5e... as long as all you need to play 5e is dice.

Fire Storm 7th level evocation

Casting Time: 1 action

Range: 150 feet

Components: V, S

Duration: Instantaneous

Tags: cleric druid sorcerer level7 evocation

A storm made up of sheets of roaring flame appears in a location you choose within range. The area of the storm consists of up to ten 10-foot-cubes, which you can arrange as you wish. Each cube must have at least one face adjacent to the face of another cube. Each creature in the area must make a Dexterity saving throw. It takes 7d10 fire damage on a failed save, or half as much damage on a successful one.

The fire damages objects in the area and ignites flammable objects that aren’t being worn or carried. If you choose, plant life in the area is unaffected by this spell.

You can find more information on this spell in: PHB.241