User blog comment:Miskos3/Fairy Tail 539: World Destruction, Review/@comment-31560299-20170616091055/@comment-7418318-20170616173635

Acnologia though had neither a reason nor a motivation to train during the one year time-skip.

Why bother to train when you just killed the only being that managed to hurt you in the last 400 years and everyone else failed to even put a scratch onto you?