I used only the Magical Units from the Council of Magi and had great success. I raised my own magic use(not hero's magic use) and gained good reputation with the council for a nice bonus. You can cover all elements with the auth deed and element changers. The debuff and slow combo(w/ archwiz) works very well too, esp. if placed strategically. This is coming from someone that played pretty far. Its a pretty OP tactic(IMO), so you might get bored tho.
 "Protector IV.V"){kind=icon}
 "Sentinels: First Wave Beta2"){kind=icon}
 "Starland Multiplayer TD"){kind=icon}
 "Protector"){kind=icon}
 "Battle Gear"){kind=icon}