Hey,
in my opinion, Lightning bolt is the best single or straight line damage spell for any mage. Hell, you don't even need any spellbooks to be a successful mage if you spec right. If you are empire side, even better.
I tested this out with a henchman. I chose mage as it's profession, no spellbooks present.
- spec mastery -line all the way eventually, although take Aeromancy pretty early as a sidestep. -30% casting cost is huge.
- spec to greater necromancy for Horrific Wail, if you are Empire side. By this time you should be around level 11.
- equip an adept/magerobe, cast Mantle of the Oceans from another champion if you have it, and all tactical spells are free.
- now, even when you have not yet specced any +% spelldamage, you are doing 60 damage with Lightning Bolt. Horrific Wails conquer you cities in 1 or 2 casts most of the time.
- also get Sunder to mow down Elemental Lords.
Who needs Spellbooks? Freakin' fun to play as a mage without them!