You send forth a bolt of lightning and fire in the form of a helix which hits a target creature you designate. If that creature fails its Dexterity saving throw it takes 3d6 fire damage and 3d6 lightning damage and you regain hit points equal to half the amount of damage dealt. On a successful save the creature takes half damage and you do not regain any hit points. 

At Higher Levels. When you cast this spell using a spell slot of 5th level the lightning and fire damage each increase by 1d6. The lightning and fire damage each increase an additional 1d6 with each odd level spell slot used. 

"Rage is not the answer. Rage followed by fitting vengeance is the answer." -Ajani Goldmane