Pretty much mage moves last and really shouldn't be exposed anyways. Also even if you get one unit close enough to an exposed mage, they could just as easily use their stockpile of mana to burn you down with Primal.
Then i win again... If they use their mana up spamming primal then they can't use chastisement next turn, meaning the rest of my army can move in and he won't be getting to use it without some good luck.