Elfire

You create a burst of flames on ground that you can see within range. The magic flames fill a 5-foot cube. Any creature in the fire’s space when you cast the spell must succeed on a Dexterity saving throw or take 1d12 fire damage. A flammable object or piece of clothing hit by this spell ignites, even if it is being worn or carried.   

The spell’s damage increases by 1d12 when you reach 5th level (2d12), 11th level (3d12), and 17th level (4d12).

As Elfire possesses relatively high Might (as compared to Fire or Thunder), it is a solid mainstay tome for Mages and Sages. It is also affordable and commonly available for purchase in shops. This spell is from the Fire Emblem franchise.