Jordi,
You should definitely set your auto-pause to stop when an enemy is spotted. This makes all the difference in the world when casting area of effect spells. Most of the time you can back up a little and plan up your actions before they spot you.
As far as touch-based spells. Use spells like Mirror Image and Stoneskin to protect your mage. These are two must have spells for your mages. If you are hit while casting, the spell is interrupted.
|