elemental strike

make a melee attack with it against one creature within 5 feet of you. On a hit, the target suffers the weapon attack's normal effects, and the target takes an additional 1d6 acid, cold, fire, force, lightning, poison or thunder damage, you choose when you cast this spell.  

this spells damage increases when you reach certain levels, at 5th level the damage increase to 2d6. the damage increase by 1d6 at 11th level (3d6), and 17th level (4d6).