by Saturnineage
The ones in the rulebook are good starter books. Here is an updated version that you can build all 4 mages at once with the core set:http://boardgamegeek.com/filepage/83267/updated-mage-wars-sp...
Here are simpler "apprentice" spellbooks too:
http://boardgamegeek.com/filepage/83113/mage-wars-apprentice...