[Gandalf Parker]

You might also add fly or blink (or those sandals) to a mage so they can jump to the back of the enemies forces and are more likely to target a commander with the spell.

But I find that Charm or Hellbind Heart are spells that work best in one-on-one situations. Scripted to a seducer, or an assassin, or used in the Arena.

You still might want to invest some army into knocking out some of his support units in case the spell causes him to do battle with his own troops. But I still get better results this way than trying to use such spells in combat.