You can also equip your own commanders with a ranged weapon and aiming items. Then set him to "Fire Rear" or "Fire at Large Monsters" if they are using mages who have high hit points in relation to the other units on the field. I used this tactic one time against a guy playing Kailasa and he publicly called me a cheater
. Many of the bow/crossbow weapons work well for this and normally have cool secondary effects. If your commander has access to air and/or nature magic you can increase his precision further with "eagle eye" (I think this is the name of the nature spell.) and "aim".