I was wondering how a Final Fantasy game like this would end up:
it's somewhat similar to a part of the plot in FF2 - the game is a lot about extremely powerful magics, magics that have been sealed because of their extreme potential, which of course means they're protected.
The thing about these spells is that they put killers like Ultima and Life2 to shame - these "ultimate magics" are even stronger, and are in a class of their own.
I don't know if the player should be able to use them, because they are overkill, but it's a pretty funny idea nonetheless.
Anyway, here are a few examples:
Ragnarok - MP: 180
this is basically a super-powered Ultima; it deals a guaranteed 9999 DMG on all enemies, multiple times - the repeats depend on the casters Magic stat (Magic/10 rounded down = amount of hits)
Doomsday - MP: 150
this magic heals all allies by 9999 HP and hurts all enemies for 9999 DMG
Healing Spirit - MP: 220
heals all allies by 9999 HP and casts Life2, Esuna and Regen on all party members
Great Guard - MP: 210
casts Protect, Shell, Haste, Reflect and Float on all party members
Start inventing your own ultimate magics!