Open Heart (オープンハート Oopun Haato?) is a finishing move used by Amu Hinamori while in the form of either Amulet Heart or Amulet Spade to cleanse X-Eggs and X-Characters and return them to their original forms. It supposedly uses the power of the Humpty Lock, since Amu is the only one who has the ability to use it.
The phrase goes by "Negative Heart, Lock On! - Open Heart!".
Fanon Description by Caramelangel714Edit
As of the rebooted movie, all of Amu's techniques are more useless than all of the precise characters, especially, all of her Character Transformations' techniques are very weak.