I posted this in another thread but i wanted to start a thread for new ideas for what the mana towers could do.
The towers should be a place where your archmages have completely mastered the genre of magic the tower represents. This should provide you with better archmages and maybe a passive empire wide bonus.
Tower ideas:
Divination- Grants archmage units the spell "Clairvoyance". it would act like a floating eye without the distance restrictions. This would be in addition to the free tech now.
Necromancy- Grants archmage units a promotion "Necromancer" this would make them into walking Mokka's Cauldrons.
Alteration- Could give your archmages a spell that turns selected enemy unit into a baboon or random animal unit. This would also let you get animal cages in late game.
Elements- In addition to current effects, could spawn a permanent summon of water, fire, aurelis, earth, and air. Or make this tower let your archmages let your summon Djinn and we can come up with a new Metamagic 3 spell.