My sov also gets death magic.  Infecting everyone with blindness goes a long way.  I also like to give her that staff of souls that increases spell damage and lets you generate mana with kills.

Never watched "Trainspotting"?  Great movie that.  Heroin is a class A narcotic.  Mainlining means injecting it into a major vein and is associated with an intense feeling of euphoria and pleasure.  I was using that as a metaphor.

Ah, ok. I thought you meant a female hero, a heroine.

Well, since  I already infected whole armies with graveseal and blindness several times, I guess I never have to try heroine. That's kind of a relief, actually.

I would take Air by itself over both Fire and Death.  

Also wouldn't need Death Worship anymore if you have Air, can trade that for a more powerful choice as well.

I think this is a topic for another thread but I'm curious, what do you get in Air that can replace all the fiery doom and maleficence that the Fire and Death spheres have on offer?  There are many ways to play the game, but for a mage sov I would think those two are pretty obvious choices.  Also, what else would you spend your customization points on?  I find most of the options a little underwhelming, which is why I always pick two spell traits.  I'd even try and pick one more if starting with that staff of souls wasn't so kickass for a mage.

Procipinee's Crown is worth having. Have a free army of summoned units, for example.

Fire is fine as far as it goes but I'd always prefer Air for Haste, Guardian Wind, Cloudwalk, Titan's Breath. Sure you need a different way of winning battles to Fireball, but there are plenty. Fireball is quite an expensive spell which takes two turns. Haste is a cheap spell which takes one turn. Titan's Breath is a battle winner on its own. With -1 casting time and/or a very high initative mage it's pretty much an exploit in that you can beat any AI army if you have enough mana and a few units to damage prone AI units.