well since your a mage don't you have transmute?
That gives u +2 mana for every kill u make IIRC
so you don't need a magic spring
as supporting unit I would go for a cyclop if you get it from the scroll
giant is bad slow speed and ini
dragons are also no use since u need to heal them and stuff
archdemon would be ok if it would spawn rage balls(dunno if this is already fixed in a patch)
Ents are not a very good choice either(see giant)
ogre also not very good
cyclops already got high res and can do ranged attack if needed
