Sorceresses are really good, especially for nonastral or astral-1 nations. You can recruit a couple of them, then script one to cast light of the northern star and have them all cast soul slay. Really, really nice.
Or mass them and just have them cast stellar cascades. Air 2 also gives you a mage to cast wind guide.
Lizard shamans can be used for magic dueling - against tien chi mages or gods with low to average astral. 5-6 lizard mages with pearls, scripted for a magic duel, have a good chance of success. Or just curse enemy SCs.
Onyx sorceresses can be scripted for dust to dust. Give them a booster and they are capable of controlling the dead, too.
All shamans can craft boots of rejuvenation, empower one or trade for a booster and they can also craft rings of regeneration and vine shields - very potent items.
Indie mages expand your possibilites greatly, they just require some creativity to be effective.