People don't believe me, but Intelligence can get ridiculous and is currently not well balanced with the rest of the game. It starts out low, and then goes way too high in the mid game. The problem is that no one really seems to get what it does. It adds Spell Mastery and Spell Resistance. It also gives bonus to experience.
Spell Mastery is our ability to penetrate Spell Resistance. Think of it as the mages skill in casting a spell.
We need a free stat, like Initiative is, to regulate spell casting times. That way the bonuses to it, which are extremely powerful, can be explicitly controlled.