Battle Mage... IMHO, useful only in the early stages when opponents are weak and can be defeated with two or three ice bolts, but Order magic is not entirely combat-oriented and is more intended for other purposes: to cause trouble!!! :D
Fist and Bolt are the only decent damage-dealing spells for a mage. They are always useful for finishing off an enemy hero or taking down a weakling with Bolt. Battle Mage is good, of course, but not War of Nature. That's truly a mistake of nature.