At the climax of my story, the main antagonist transforms into a gigantic and nigh-unkillable monstrosity that resembles an unholy hybrid of a crocodile, Mosasaurus and Dimetrodon. After a long and destructive battle, he is finally killed when my deuteragonist unleashes a powerful energy beam from her sword (Excalibur-style) that destroys the antagonist by completely vaporizing him and overtaxing his healing factor. This form that the antagonist takes is basically a scaled up saltwater crocodile (with a tail fluke akin to that of Mosasaurus hoffmanni along with a head and sail-like structure on its back similar to that of Dimetrodon angelensis) measuring 80 meters long from snout from tail.
Although, I was unable to calculate this creature's weight, a combination of basic investigative skills and the wonderful accessibility of Google Search enabled me to find out the density of an adult crocodile is 948 kg/m^3. It is to my understanding that vaporization is basically when a substance in a liquid state changes into a gaseous state due to an increase in temperature and/or pressure (please feel free to correct me if I am mistaken).
How much energy would be needed to achieve such a feat?