Sphere casting towers.
Hello, so as I'm sure the devs are aware a good number of us players are unhappy with the way wizards can pretty much slaughter entire armies with one or two castings of certain spells.
And against a siege it's just plain laughable if one guy has a wizard and at least a semi-decent army to act as a bodyguard for him.
One idea I had was, how about a "tower" upgrade that casts a sphere spell surrounding the walls so that meteor shower or lightning storms or other completely OP spells that burn down entire cities actually have a counter to at the very least REDUCE their damage.
This would actually require some strategy again as you can't just roflstomp the dang city with magic.