Storm Bolt( Complete Mage, p. 47)
The electrical energy contained within your magic rages inside you, begging to be released.
Ability to cast 3rd level spells,
As long as you have an electricity spell of 3rd level or higher available to cast, you can fire a 20-foot line of electricity as a standard action. This bolt deals 1d6 points of electricity damage per level of the highest-level electricity spell you have available to cast. A successful Reflex save halves damage. As a secondary benefit, you gain a +1 competence bonus to your caster level when casting electricity spells.