As I've been saying for a while now, the Mage is way stronger than the Paladin in the end. Haven't played as a Warrior but I get the idea this is even worse. The problem is that on Impossible you play against I think 170% stack enemies with only 60% money. So in theory this should be a challenge. Wrong. A Mage can still dominate by using offensive spells correctly. All you need is:
Chaos 3
Destroyer 3
High Intellect
Fireball, then Ice Snake, then Fire Rain
Higher Magic when you can get it
Orc Shamans and Royal Thorns to spam the battlefield
And you just destroy everything that moves with your spells. It doesn't matter that the stacks are 170%, nor does it matter that you only get 60% gold. I am up to level 15 on Impossible as a Mage now and I have 500,000 in the bank.
Impossible Mage is not impossible, in fact it's not even difficult. So Mages need nerfing.