[Lazy_Perfectionist]

What spells have you tried in combat?

If money is limited, but recruitment points aren't, consider mage engineers. You can also bootstrap fairly high into earth, though you'll be restricted by gems and fatigue limits.

Summon Earthpower will take you to earth two, and you can use further gems to cast as high as earth three. As many as two gems per spell, but earth three. So no fatigue 300 spells, since you can't use the minimum gems. Fortunately, a lot of earth spells are low fatigue, and you can cast some worthwhile ones without additional gems.

Earth Meld should be ignored, however, as should air's Fetters. They roll against strength and magic resistance.

That's about all I can offer at the moment, w/o a manual at hand or an online spell listing to refresh my memory.