The phrase goes by "Negative Heart, Lock On! - Open Heart!".
Other techniques that may be used to cleanse X-Eggs/ X-Characters are:
- Seraphic Charm's "Angel Cradle"
- Amulet Clover's "Remake Honey"/"Remake Honey Special"
- Amulet Heart and Platinum Royale's "Platinum Heart"
- Yamato Maihime and Clown Drop's "Queen's Waltz"
Shugo Chara!! Doki-In season two of the anime, Amu learns to use a stronger version of Open Heart to cleanse Wishing Eggs and remove corrupted Character Transformations caused by antagonist Lulu's ruby necklace. She can also use it to purify X-Eggs and X-Characters.
Shugo Chara! Party
In episode 24 of season three, Amu, while in the form of Amulet Dia uses an even stronger version of Open Heart to cleanse and restore X-Eggs with Rikka Hiiragi, who is in the form of Pure Feeling. The enhanced effect of this ability also restores broken X-Eggs.
- In the first Season when Amu purifies a mass of X-Characters at once they are never shown being purified, only a shot of Amu is used instead. This presumably due to the fact that Open Heart shows the X-Character's true form before it returns to its egg and most of the X-Characters there were never even shown.