Qual é a contra-maldição para Sectumsempra?

Não sabemos exatamente o que é o contracursor, apenas que existe um.

A principal coisa que sabemos sobre isso em canon (consulte a página HP Lexicon no site Chamado de "countercurse Sectumsempra") é da cena no livro 6, capítulo 24, onde Snape usa para curar Malfoy. Por sorte, esta passagem do livro é disponível no Pottermore :

The door banged open behind Harry and he looked up, terrified: Snape had burst into the room, his face livid. Pushing Harry roughly aside, he knelt over Malfoy, drew his wand and traced it over the deep wounds Harry’s curse had made, muttering an incantation that sounded almost like song. The flow of blood seemed to ease; Snape wiped the residue from Malfoy’s face and repeated his spell. Now the wounds seemed to be knitting.

Harry was still watching, horrified by what he had done, barely aware that he too was soaked in blood and water. Moaning Myrtle was still sobbing and wailing overhead. When Snape had performed his counter-curse for the third time, he half lifted Malfoy into a standing position.

"You need the hospital wing. There may be a certain amount of scarring, but if you take dittany immediately we might avoid even that … come …"

Então, tudo que sabemos sobre esse feitiço é que é um encantamento que soa quase como uma música e que aparentemente precisa ser executado três vezes para ser eficaz.

A cura de George Weasley no livro 7 (também mencionada na página HP Lexicon acima relacionada) acontece fora do palco, então não temos mais informações sobre essa cena:

Glad of something to do, Harry pulled him free, then headed through the empty kitchen and back into the sitting room, where Mrs. Weasley had staunched his bleeding now, and by the lamplight Harry saw a clean, gaping hole where George’s ear had been.

"How is he?"

Mrs. Weasley looked around and said, "I can’t make it grow back, not when it’s been removed by Dark Magic. But it could have been so much worse... He’s alive."

Existe um, mas Snape provavelmente terá que ensiná-lo a você.

Como sabemos, Harry aprendeu o feitiço do livro de poções que uma vez pertenceu a Snape, e Snape era o "inventor" do feitiço. É lógico que Snape fosse também o inventor da contra-maldição.

A cena do filme vem da descrição nos livros

The door banged open behind Harry and he looked up, terrified: Snape had burst into the room, his face livid. Pushing Harry roughly aside, he knelt over Malfoy, drew his wand and traced it over the deep wounds Harry’s curse had made, muttering an incantation that sounded almost like song. The flow of blood seemed to ease; Snape wiped the residue from Malfoy’s face and repeated his spell. Now the wounds seemed to be knitting.

Harry was still watching, horrified by what he had done, barely aware that he too was soaked in blood and water. Moaning Myrtle was still sobbing and wailing overhead. When Snape had performed his counter-curse for the third time, he half lifted Malfoy into a standing position.

_{Harry Potter and the Half-Blood Prince}