How would you beat my missle troops?

[En Forcer]

Well it is pretty early in the game (turn 40ish) so I still have some spells to obtain but I'll be on the lookout for those fire arrows. Also, what do you think of that Air spell that improves Aim? Worth it?

I'm alchemy-ing like mad to get 50 air gems so I can empower my guy with Air Magic so he can use that spell...

Any other good spells for a squad of archers?

Some other thoughts I had was smaller Groups of missle troops (rather than all in one big batch) so they might focus on different targets and not be so vulnerable to area affect spells.