Your favourite Game Breaker in Kingdom Hearts?

[TwilightLord]

I know of another Game Breaker in Kingdom Hearts Birth by Sleep that arguably outshines them all: the spell Mega Flare. It does high damage to all enemies over a large radius, executes quickly, and the damaging part of the attack lasts for several seconds so if you're in an area where enemies spawn in waves you can damage multiple waves at a time. Plus, if you know how the Command Board works, it can be obtained as soon as you leave the Land of Departure. Level up three Fires and two Aeros, fuse two of the Fires into Fira, fuse that with the third Fire to get Firaga, fuse the Aeros into Aerora, and then fuse Firaga and Aerora into Fission Firaga. Now repeat the process with the Fires to get a second Firaga (or if you have the cash, just buy one from a Moogle), and fuse that with Slow to get Crawling Fire. Now fuse Crawling Fire with Fission Firaga. Congratulations, you just got Mega Flare before you even got to your second world. Have fun blazing through most of the normal storyline in seconds. Unfortunately, this doesn't work in the Final Mix version - they nerfed Mega Flare by doubling the recharge time.