Board Thread:General Discussion/@comment-4698889-20170224092621/@comment-25926003-20170302140614

You're all assuming that the prologue IS during the JoC period, when from the look of it it's during the Second Period, prior to Levia and the gang becoming gods. Allen and Nemesis most likely travelled back in time to a point where they could get Levia to agree to do her swap technique (IE a point where Levia is able to do the technique, and doesn't have any grudges yet that'd make her give a flat out "no" as an answer).