User blog comment:IamJakuhoRaikoben/Chapter 433 & 434: Ikusatsunagi & Demolition Fist, Review./@comment-76.121.234.236-20150512023224/@comment-1776824-20150512184814

E.N.D.'s everything is sealed in that book. This is legit just Natsu basically becoming a human dragon. At this point, he is as strong, physically, as Igneel from the Tartarus arc, and by the end he'll probably be as strong as him physically from his prime when he was alive, which is what will need to happen for him to defeat Acnologia. But don't you worry, when he eventually turns back into E.N.D. there'll be a massive powerup that will stick with him forever and give him that extra boost in strength, and at that point he'll need it. At this point? Hmm...not really liking how much stronger he is after just one year. >_>