User blog comment:Miskos3/Fairy Tail 541: The Magic of Hope, Review/@comment-7418318-20170626210449

Hey I just thought of something... maybe once Lucy & Co imprison Acnologia's body in Fairy Sphere, his Astral form might suffer from some kind of backlash from that, making him vulnerable to the DS's attacks.

That would be a nice way to keep him a potent threat, but at the same time pull him down far enough to be defeatable with neither power of friendship nor any other kind of bullshit.