[Sombre]

Speaking just of SP and facing down the AI, the most dramatic way to see the power of spells is to take EA Abysia and expand and hire mages to research as normal until your mages have researched both phoenix power and falling fires. Then take a huge chunk of your research mages and join them up with a reltively small army. Script them to PP then FFx4. If you have a critical mass of them, it doesn't matter what the enemy is throwing at you, they'll burn it to a crisp in a few rounds.

The difference between this and an army, again speaking purely in SP terms, is that an army will take casualties against the AI. A critical mass of mages with some blockers will not.