[Yrkoon]

If you want to take out commanders, "Fire archers" is probably what you want since, as Shovah pointed out, commanders cannot be targeted specifically.

Commander are usually at the rear not far from the archers and a stray arrow might hit the commanders. If the commander is a mage, then he will die most of the time. If it's a non-mage, the wound might make it rout, and his men with him.