As you play through the main FFX story you can find one MP Sphere in a chest in the Cavern of Stolen Fayth, and the bosses Lord Ochu and Sin’s Core both drop x1 each. But all those are one-time things. So to actually farm these spheres, you’ll need to unlock & fight Vidatu. This creature is unlocked after capturing 4 of every Imp-type fiend in the game, and there are only three of them:
Gandarewa: Found on Mushroom Rock Road Aerouge: Found on the Thunder Plains Imp: Found in the Cavern of Stolen Fayth
What Are MP Spheres Used For?
MP Spheres change an empty node on the Sphere Grid into MP +30. That’s all they’re used for when it comes to the Sphere Grid. They don’t even provide any abilities through customization or for your Aeons. But they can, however, be used in Rikku’s mix Overdrive. Some standout examples include: Mega Mana (Ether + MP Sphere): Doubles the party’s max MP. Super Mighty G (Chocobo Feather + MP Sphere): Casts Protect, Shell, Haste, and Regen on the party. Quartet of 9 (Amulet + MP Sphere): One character deals 9999 damage with every attack.
Are MP Spheres Worth Farming?
No. MP management gets easier and easier as the game progresses. MP recovery items become much more available, the Sphere Grid naturally gives you tons of it, and both Yuna and Lulu’s Celestial Weapons have One MP Cost on them – which just about negates the need for high MP anyway. Even most of Rikku’s mixes can be created with other, easier to obtain items. So don’t waste your time going after MP Spheres too much.