User blog comment:Water Dragon Slayer/DREAM BATTLE CHRONICLES: SECOND MATCH!/@comment-89.242.95.219-20130724063937/@comment-7418318-20130724073922

Mavis' tactical genius has one big hurdle against Zeref: Lack of information.

What we know about Zeref are all ancient legends and superstition. Even the legends about his death or sleep that were widely believed turned out to be just stories without any truth in them, so how much of the other information about him is true?

And with magic that immediately kills if you fail to dodge or ward against it, you don't really have many opportunities to analyze during the fight.

So for me the situation is pretty much like the previous dream battle. I want Mavis to win, but I don't see how she could, unless the battle is extended to allies and servant (Mavis + Fairy Tail vs. Zeref + demons). While such a battle would leave Fairy Tail with casualities, those death might buy Mavis enough time to come up with a way to defeat Zeref.