I dont know if it has been mentioned, but i think the cast times for most spells should be greatly reduced.

One option would be a slider, more mana per spell for faster casting, that would keep the balance in the beginning when mana is scarce and a round isnt much compared to late game when mana is abundant but you will always be interrupted casting long spells or cast 1 spell/round.

I would also like to see unit enchants to be cut in half (atleast) but only in combination with above mentioned reduction in cast times. That way i cant as easily produce super units but it would also be worth it to be cast on weaker units.