User blog comment:Miskos3/Fairy Tail 538: When the Flame Goes Out, Review/@comment-26099879-20170603150011/@comment-7418318-20170604062508

It could also be a mistranslation with the actual title being "End of the World" or somesuch on account of the Dragon of the Apocalypse coming back and being pissed off.

I would be surprised if the first thing Acnologia did after breaking out is levelling a few mountains to vent before sniffing out the Dragon Slayers. That could surely seem like the end of the world has come to anyone nearby.

But I think the theory which Soul quoted is also a possibility... and if done right a rather intriguing one, but with just a couple of chapters left there is hardly enough time to properly flash out such a scenario, so I doubt Mashima will go down that road. He could of course just rush throgh it with a minimum of explanation like he did several times in this arc already...

If it turns out to be the obvious and Acnologia does come back, I hope this ordeal severely weakened him. Because the way he was before being sucked into the time pocket, he should really be undefeatable, even if the entire cast teamed up. Better to have him weakened so it makes at least a bit of sense for him to lose. Even if he's put down a few pegs, he's still a most formidable opponent.