[Zen]

D.) Yes. But only if the spell had >=199 Fatigue. If it is more than that, the spell will not be cast or you must use more gems in order to lower the fatigue level below 199 to cast it.

The AI will not cast things spells based on the fatigue system that will cripple or potentially kill them. So a hardline number of 199 Fatigue (after all gems) is adhered to.

So if your 6Path spell has a fatigue cost of 100, then you could cast the spell in the manner you described. If it has a 200 or 300 Fatigue, it will not be cast without more gems to fuel it (and that you cannot use because of the gem booster system).