Ember Belly

You swallow the oil consumed in the casting of the spell. Once before the spell ends, you can exhale the oil as a bonus action, igniting it as you expel it from your body. Each creature in a 5-foot-wide, 30-foot-long line must make a Dexterity saving throw, taking 2d10 fire damage on a failed save, or half as much damage on a successful one.

Once you exhale the oil, the spell ends.