[Quitti]

All true Illuminated one, but there are situations where I try to optimize gem usage enough (saving for a global spell, or simply not having a big income and/or have other uses for the gems). Of course when using Shadow Blast still as an example - just give one gem to the mages, they won't use more, but incidentally getting them to cast a second spell might very well require 3 gems per mage instead of 1/spell. That's suddenly 50% increase in gem usage, when we're talking about 10-20 mages that will be noticeable. Still, what most matters with (big) aoe spells is the humongous 'alpha' strike that decimates the opponent, but if the first wave of spells is not enough to do the damage you want, you wouldn't want to spend extra gems to fire up a second volley which could very well be used for better purposes.