Gem Use for Fatigue/Boosting Skill

[Mysterio]

Originally Posted by Shadrach

My test showed an E3 mage using four gems to cast Earthquake after using Summon Earthpower, so boosting with spells definitely lets you cast things you couldn't cast otherwise, and also use more gems than you could otherwise.

Actually, you didn't prove that. As an E3 mage, he's allowed to use 3 gems max total for boosting his path + paying the cost to cast the spell. Since Earthquake (an E4 spell) costs 3 earth gems, he can not boost his path by +1 with a gem (he'd need 4 earth gems total when he's only allowed to use 3). But casting Summon Earthpower boosts his path to E4 for the entire battle, so he no longer needs to use a gem to +1 boost. At E4, he's now at the level required to cast it and uses the 3 earth gems to pay the spell's cost.