User blog comment:FairyRaven/Fairy Tail Chapter 368: The Third Seal, Review and Commentary/@comment-24066070-20140127014759/@comment-33019320-20140127213619

Now that I think about it, Fairy Sphere is going to be absolutely useless since the attack is coming from inside the guild not outside. Since Acnologia attacked Tenrou Island from the outside, it was extremely effective but then again, what's the point of a shield if the enemy has already bypassed your defenses and is already attacking the inside. Sure, it might freeze the attack midway but it's probably going to continue once time unfreezes.