1)global enchantments: enchantments that affect everyone and everything. Like "all empire troops function at +2 Atk. " or "all spells cost 50% more except for the casting player. Lots of options for interesting spells.
2) strategic casting times: I liked the mama based one in mom. Here it could still be mana per turn usable, but increasing that limit could be done Through Mage traits and maybe some general ones.
3)interrupts: being able to interrupt spells being cast by other players would add to the interesting. Not guaranteed though, chance to dispell that could be different for different spells.
4) dispells: being able to dispell global, or city enchantments.
5) damage shields: more damage shields would help offset the abusability of maul
6) it needs to be easier to remove enchantMents from units. Like it is from cities.
7) notifications when other champions cast spells on units or cities you can see. Or globally if that is added.
8) the ability to discuss specific enchantments or spells being cast in diplomacy. "stop casting night of the living dead or we will go to WAR!"