Ratchet & Clank Future: Tools of Destruction Final Boss: Emperor Percival Tachyon
The final battle against Emperor Tachyon. It starts off hard until you figure out which weapon can make mincemeat out of him. That bums me out because the R&C games usually have such awesome, intense final boss fights.
Skip to 8:50 to see me discover how OP the fully-powered flamethrower is.