Granblue fantasy

Apparently, an overly brilliant alchemist figured out a way to defeat one of the strongest characters in the storyline in just ten minutes.

No, there's a whole story behind it. A secret laboratory, a setup by Belial, who deliberately left the information, and so on.
Although, I repeat, it would be funny if Clarissa was involved, Calioostro messed up, and she just went ahead and nuked him with an atomic explosion.