Simple but ironic question about gems and casting.

[Graeme Dice]

Vicious Love said:
I was under the impression that spellcasting could only bring you to the threshhold of HP damage, and only fatigue-inducing spells and negative reinvigoration could actually inflict said damage. Never once seen a mage injure himself with spellcasting, even when he was at 97 fatigue or so and cast a spell which would ordinarily bring him all the way up to 200 fatigue.

That's exactly what I just said. Mages cannot cast any spell that would bring them above 200 fatigue. They must use sufficient gems to bring the spell down to a fatigue level that would allow them to cast it and end up at only 200 fatigue.