Disable:

MP cost. compared to magic costs on FF7 i'd say 200MP.

silence, vitality 0, blind, slow and mini on all enemies and drains all Mp. reduces HP to 1. completely unblockable against normal enemies. bosses can resist some effects.

it basically puts the enemies at your mercy. they have no defence. no way of attacking for more than 1 damage and will most likely miss.

ultra-buff:

heals all allies by 9999 HP and casts Life2, Esuna and Regen casts Protect, Shell, Haste, Reflect and Float on all party members and auto life. all attacks and healing, heal 9999 or inflict 9999 points for the rest of the battle and limit breaks, overdrives and all forms of special attacks are full. you get a 50% stat boost for everything.

i think that seems as this completely sets you up for any battle it depleted the casters MP for the rest of the battle and s/he can only cast it if MP is on 999.