One thing I had never done before was play a character born under the Atronach. The Atronach gives you 150 boost to magicka, gives you 50% spell absorbtion, and takes away magicka regeneration. What I didn't realize, is that you can't wait or sleep to regain your magicka, making a character with this very tough to play at times. This is a good thing, as it becomes a challenge, I just want to know some of the best ways to overcome the challenge, and keep the game fun for a mage class character under the atronach. Destruction seems like a poor choice, since its a Wisdom spell, and all Wisdom does is increase the rate at which you regenerate magicka. I will likely go with Conjuration as my main, and Illusion as my back up. Calming things so they don't attack me, turning invisible, making people like me, etc. Have you guys ever played under the Atronach? What did you do?

I did an atronach once. It really changes how you play the game. You will need to get good at alchemy, and start churning out Restore Magicka potions. Steel Blue Entomola, Flax, and Bog Beacon Asco Cap are your best friends here. You can also use altars to regenerate your magicka, Ayleid Wells, and I think wayshrines (but I am not positive about those).

If you live in Bravil, you can top off all you want at the Lucky Lady.
Seek gear to boost your spell absorption from 50 to 100%.
When you have good spell absorption and skill in mysticism, you can cast telekinesis spells to fill up your blue.
Wills-o-the-wisps are lovely little refilling stations.

More here: http://www.uesp.net/wiki/Oblivion:The_Atronach#Atronach (follow some of the sublinks).