So, since boredom is real, I decided to do a Minecraft calc if I could get anything beyond Building, and guess what I did. First time I ever used things like Vaporization in calc, so I may have screwed up, but there it is.
Here we can see the EnderDragon's hitbox dimensions. It is 16 by 14 by 8. Each Block is a meter cube according to WoG, so together it makes 1792 meters cube. Thus making it 1792000000 Centimeters cube.
The Dragon can vaporizes it's body size worth of steel and other material. It's vaporization because the Dragon can destroy large bodies of water without a trace. Pretty it wouldn't happen with Pulverization.
According to CrazyStarf's blog, value for vaporizing steel is 60117.42 joules, so using our CM2 values, we have 107730416640000 joules, Town Level+
EDIT
According to Darkanine, the value for vaporizing Iron is 6,213,627 joules/cc. So using that with our previous volume gives us 11134819584000000 joules, which is Small City level+