Originally Posted by Maylander
Get mana regeneration as soon as possible, and pump Ancient Knowledge as high as possible. Whether you use lightning, ice lance or fire is irrelevant as long as you have high enough AK and the mana regen skill.
There's a guide on the JoWood forum that gives some help on this. Half your AK level adds to the damage and getting the specialized perk in a magic school (water, fire,druid) doubles the base power of all spells in that school.