The Door of Vows.While Lucy studies the Book of E.N.D. for a way to sever Natsu's connection to it, Natsu expends his Dragon Force to destroy Zeref, only for Zeref to use Fairy Heart's power to rewind time and restore himself. After mortally wounding Natsu, Zeref reopens the time rift to transform Fairy Tail's front door into Neo Eclipse, which also makes the rift visible, forcing Jellal to risk his own life trying to push Acnologia into the rift...