User blog comment:B214/Chapter 498: Gray vs. Invel/@comment-130.105.140.154-20160822141318/@comment-130.105.140.154-20160826113005

Personally, these Spriggans motive is to kill, kill, kill, and Zeref wants death and destruction. Fiore is now devastated, and seeing that Fairy Heart is now in the hands of those villains, I can guarantee that Alvarez is winning the war. Four of the Spriggans are very, very, very powerful beyond comprehension, yet we know nothing about how they became who they are.

And for me, Irene saying that the main reason for taking Fairy Heart is to take down Acnologia is BS. Honestly, I don't know what they're trying to accomplish taking down Acno. For all I know, they will destroy all innocent beings in the world, cause it's already established that Zeref's goal is to destroy humanity.