Counterspell is a boring way to fix aoe spells
Before 0.85 aoe spells (fireball, blizzard, ...) were overpowered, but now the player can either wipe armies with them if no enemy mage is there or the enemy mage counters the spells. This makes the spells boring, because they are either overpowered or useless. It would be much better to make ALL spells resistable and to reduce the effect by 50 % on a successful resistance check. Counterspell should improve the spell resistance of a single target by 10 and mass counterspell should improve the spell resistance of all targets by 10, but costs more mana.