A creature within range burns. While it is burning, at the start of each of its turns, it makes a Constitution saving throw. On a failure, it takes 15d8 fire damage. On a success, it takes half as much damage and the effect ends for that creature.

If a target takes fire damage from this spell, choose one creature you can see within 30 feet of target that is not already burning. The new target begins burning, taking damage and spreading the fire in the same manner as the original target.