Hi everyone,
The desscription of each magic skill (air, fire, earth, ice) says that putting points into the skills makes each "more efficient". However, this can be loosely interpreted to mean that skilling up to use the "improved" version of the main offensive spell (for example, improved ice bolt) will increase that spell's power.
(I scoured the forums for this answer, and indeed someone else asks it in another thread, but no one noticed his question amidst speculation regarding how to play solo as Toruum.)
For comparison, if you level up swords your accuracy and attack power increase. Is it likewise worthwhile to level up a spell school beyond the "improved X" spell level if you don't care about the specific perks gained after that? +100 cold resist, for just my mage, doesn't seem worth putting 50 points into, especially considering around 50 points is all he's going to get for the whole game.
Thanks!