Enchanted Candle

The Enchanted Candle is a magical item featured on ABC's Once Upon a Time, it can be used to save someone's life, but you must sacrifice a life for it to work.

History
Snow White's mother Eva has a mysterious illness. Desperate to help her mother, she turns to magic. Johanna, a royal servant tells Snow of a secret of her mother's, the Blue Fairy. When Snow goes into the woods she has trouble finding her, suddenly she turns around to find this fairy behind her. The fairy tells her that although it is against the rules, she will give her a way to save her mother. She summons a candle and advises Snow to use it. There's a catch though, she tells her that to save a life, she must take one. Snow must whisper the name of the victim while placing the candle over them, the Blue Fairy also tells Snow never to speak of it again. Although it could've been used, Snow cannot bring herself to kill, she tells her mother about it, and Eva tells her daughter that she is proud of her for not taking a dark path. After speaking with her daughter, Eva dies. At her funeral, Cora appears, revealing that Eva was not sick, but Cora poisoned her. It is also revealed that she was disguised as the Blue Fairy to turn Snow down the wrong path, destroying Eva's legacy.

In Storybrooke, Mary Margaret opens a cabinet to get a dying Mr. Gold a blanket. When she opens the cabinet she sees the candle she encountered in the Enchanted Forest as Snow White. He tells her he is saving it for a rainy day. Because he is so severely injured, and Cora has his dagger, he asks Mary Margaret to use it to kill Cora and save him. She asks him why she would use it for him, when she didn't use it on her own mother. Mr. Gold brings up his newly discovered connection to Henry, as his grandfather. It seems like an impossible task for Mary Margaret, but Mr. Gold tells her that she can use the candle over Cora's heart, because it is no longer in her chest, then place it back in her body. During a battle with Cora and Regina pinned against David, Emma, Neal and Mr. Gold, Mary Margaret runs out of Mr. Gold's shop, and into Regina's Vault to find Cora's heart. She lifts the heart out of it's box, whispering Cora's name. Regina later sees that her mom has pains near where her heart should be, and goes to find her heart. When she gets there, she asks Mary Margaret for the heart, but Mary Margaret tricks her, giving the heart for Regina to put inside her mother's chest. Regina accepts, and inserts her mother's heart, before her mother can kill Mr. Gold. Cora smiles and hugs her daughter, but collapses soon after. Mr. Gold is healed, regaining his full powers as the dark one. Mary Margaret runs in soon after Cora dies, telling Regina not to put the heart back, but it's too late. She looks up from her mothers corpse, blaming Mary Margaret for killing her mother.