User blog comment:IamJakuhoRaikoben/Chapter 361: The Two Bombs, Review./@comment-24066070-20131122224003/@comment-7418318-20131123072412

Throughout the entire battle we have yet to see Jackal take the situation serious.

I think he didn't use that prison spell on Fairy Tail because he enjoyed toying with them, showing his powers bit by bit to slowly crush their confidence and make them suffer.