User blog comment:IamJakuhoRaikoben/Chapter 464: Natsu vs Zeref, Review./@comment-153.91.253.204-20151130200254/@comment-153.91.200.65-20151201191506

All the power natsu has shown up until now has been his own power.The power he used against zeref is the power that he was talking about that can only be used once. If all the power he was using up until now was igneels power it wouldn't make sense considering how he said it can only be used once. He spent the last 10 months training to harness igneels power but that doesn't mean he only spent that time training to use igneels power which is what you must be assuming.