User blog comment:IamJakuhoRaikoben/Chapter 455: Magnolia's Defensive Battle, Review./@comment-5268982-20151005100114/@comment-7418318-20151005101436

Zeref seemed to know all that was going on with Tartaros, so it might have been Zeref himself who was ingrigued by her summoning of the CSK.

If that's the case it must have been quite the bummer for Brandish to learn that the person who Zeref was interested in was already captured by her subordinate and she ordered her release, only to be sent off to capture her again. ^^