Earth Attack

[Cohen]

Unless it's late game and enemy could have tartarians or earth kings or troll king a Dome of Flaming Death should work well in killing or damaging the enemy mage but this won't protect.

All domes are good except the Corrupted one that is pretty strange and from text, damages the units under his coverage.

Probably you can't afford to equip every your guy with items, so or you script some spells or you try to assign bodyguards (useful mostly to give time to your mage to prepare or kill the enemy).