Chimera Brains can be found in the northwest part of the Calm Lands and they’re not too rare. Also you can steal Lv. 4 Key Spheres from the Monster Arena creation Nemesis, which has them as a common steal. This requires a lot of setup though. Nemesis is unlocked after capturing ten of every monster in Spira, as well as defeating all the other Original Creations in the Monster Arena. So it’s a substantial amount of work to go the stealing route for more Lv. 4 spheres. But as you progress in the main story you’ll find Lv. 4 Key Spheres in chests on Mt. Gagazet, Inside Sin, and in the Omega Ruins.
What Are These Used For?
Lv. 4 Key Spheres are used to unlock level four locks on the Sphere Grid. To unlock every Lv. 4 lock on the grid you’ll need x12 of these spheres in total. And in FFX, unlocking those locks is really the Lv. 4 Key Sphere’s only purpose. But it’s important! All of the most powerful spells, such as Ultima and Flare, are locked with fourth-level locks. You can be assured that spending a Lv. 4 Key Sphere will always reward you with something great. And if you’re so inclined, Rikku can also utilize these spheres in some mighty mixes: Trio of 9999 (Winning Formula + Lv. 4 Key Sphere): All current allies deal 9999 damage with every attack until the end of battle. Super Mighty G (Chocobo Feather + Lv. 4 Key Sphere): Casts Shell, Protect, Haste, and Regen on the party. Super Elixir (Antidote + Lv. 4 Key Sphere): Cures all negative statuses and restores the party’s HP and MP to full.
Are These Worth Farming?
Yes, if you need more for your Sphere Grid then absolutely. Lv. 4 Key Spheres are what open the path to some of the best abilities and spells in the game. Think of earning these spheres as the beginning of your journey to maximum power. It may take time (and some gil) but trust me when I say it’ll all be worth it in the end.
