[Finalgenesis]

Mage will not try to save gems for multi gem spells.

I go by the rule that AI will always burn as many gems to cast a gem spell at below 40 fatigue, and this seems to work for me most of the time. So do your calculation using this rule of thumb (taking into account magic dom, encumbrance), then add +1 extra just in case and you should almost always be able to get more then 1 gem spells out. Of course it they can't burn any more gems then their path.

I think there might be an AI rule that if they are about to go above 100 fatigue from a spell, they will burn as many gems as possible to stay below 100, even if the spell does not need gems.