Malfoy spots Harry and casts a Cruciatus curse; Harry, defending himself, using the Half-Blood Prince's Sectumsempra spell without knowing its effects. To his horror, it gashes Draco's face and chest, spilling his blood everywhere.
Sectumsempra was a curse invented by Severus Snape that lacerated the target and caused severe haemorrhaging. Snape created it as a student of Hogwarts, with the intention of using it against his enemies, likely including the Marauders, with it becoming one of his specialities.
It is pertinent to mention that Harry only knew Sectumsempra was for enemies and that to him, was reason enough to use it in his duel with Draco Malfoy that took place in the boys' bathroom.
Vulnera Sanentur was the song-like incantation of a healing spell and counter-curse to the Sectumsempra Spell, which was invented by Severus Snape. While sectumsempra was invented by Snape, Vulnera Sanentur is often mistaken to be invented by him as well.
Yes, he did. Against Severus, who blocked the spell. Or curse, if you prefer. The excuse Harry had for using it the first time “I didn't know what it could do" can't be used to justify his use of it a second time, when he knew full well what he could do.
Harry Potter and the Half-Blood Prince (1/5) Movie CLIP - Harry vs. Draco (2009) HD
Is Sectumsempra a unforgivable curse?
There is likely a good reason that the Sectumsempra is not an unforgivable curse. It's mostly because Sectumsempra is Snape's personal curse that he created. It is not a widely known or used spell, and it is one that he kept secret — which means it can't be added to the list since no one really knows about it.
Vulnera Sanentur was the song-like incantation of a healing spell which was used to heal deep wounds, which could also be used as the counter-curse for the curse Sectumsempra.
Family. Snape's family background is mostly shown in flashbacks during the course of the last three novels. Snape was born to Eileen Prince, a witch, and Tobias Snape, a Muggle, making him a half-blood (hence the name, "Half-Blood Prince").
Sectumsempra is a curse invented by Professor Severus Snape, during his childhood, when he was known as "The Half-Blood Prince". He created it with the intention of using it against his enemies, and it soon became one of his specialties.
But many people forget that he also invented a number of spells. In the Harry Potter movies, Snape came up with the Sectumsempra curse when he was a student at Hogwarts, and it's known to cause painful lacerations on the target.
The injury was caused by Snape's Sectumsempra spell in order to stop the Death Eaters from hurting George (who he thought was Harry) and Lupin, but missed and hit George. Hermione and Kingsley then arrived, both unharmed, followed by Arthur and Fred Weasley, both concerned for George.
When Harry critically injured Draco Malfoy with the Sectumsempra curse, it was actually enough to have him expelled, as Professor Minerva McGonagall stated Harry was lucky not to have been, due to Snape giving lenience to prevent others from finding out that he was the one who invented the curse.
Although healing magic could usually heal injuries without scarring, with dittany being one of the more effective, injuries caused by Dark Magic usually left scars that could not be healed, as Severus Snape expressed possibility that Draco Malfoy may have had some scars from the Sectumsempra curse, and Bill's scars ...
His tears were due to the fact that since the bird had died, he had failed once more to repair the Vanishing Cabinets. Draco needed to repair them in order to give the Death Eaters a safe way to infiltrate Hogwarts. Failure meant death, Voldemort had made that very clear.
In the final movie, Harry Potter and the Deathly Hallows pt. 2, Molly first hits Bella with a spell that freezes her, most likely Petrificus Totalus. Then, she launches another one that shatters her entire body into pieces, which could be expelliarmus, bombarda, stupefy, or any spell that can produce such an effect.
The Disarming Charm became Harry Potter's signature spell, and it notably caused the final defeat of Lord Voldemort during the Battle of Hogwarts by rebounding his Killing Curse, because the Elder Wand recognised Harry as its master through the spell connection, and thus strengthened the Disarming Charm to the point ...
Snape's death by Nagini highlighted his loyalty to Dumbledore and Harry, showing his true allegiance in the end. Voldemort used Nagini to kill Snape instead of Avada Kedavra, possibly signaling a hidden respect or hope for Snape.
The Killing Curse was created in the early Middle Ages by Dark witches and wizards. Primarily, the curse was used to quickly slay opponents during a duel. In 1707, the Wizards' Council was restructured into the Ministry of Magic, which allowed for more strict restrictions on certain types of magic.
Harry yells “Sectumsempra,” the hex scribbled in the margins of the Half-Blood Prince's book. Blood spurts from Draco's face and chest, and Myrtle beings screaming. Snape bursts into the room and heals Draco's wounds almost immediately. Snape hurries Draco to the hospital wing, commanding Harry to wait behind.
Although he wasn't turned into a werewolf, he did develop some wolfish tendencies such as a liking for very rare steaks. He married Fleur on 1 August 1997, although their wedding was disrupted by the arrival of Death Eaters following the fall of the Ministry of Magic.
The movies follow the books closely enough that they aren't really separate universes, except for the fourth movie. There isn't any truly compelling evidence that Snape is Harry's father, because all the points you raise are explained. Snape hated Harry because Harry reminded him of the man who "stole" Lily.
Under the influence of her father, Dolores grew up despising her mother and brother for their lack of magical abilities. She was sorted into Slytherin House at Hogwarts School of Witchcraft and Wizardry and hated her time at the school due to never being given any positions of power.
In Harry Potter and the Deathly Hallows, Fred and George are members of the Order of the Phoenix and serve as two of Harry's six decoys when he escapes Privet Drive. George loses one of his ears to Snape's Sectumsempra curse (which was aimed at a Death Eater's wand hand, but missed).
He grabbed the group in the cellar and disapparated just as Bellatrix Lestrange threw a knife at them, which hit Dobby in the chest, killing him. Some viewers that this moment meant that Dobby broke his promise with Harry, but he never technically agreed to the wizard's wishes.
Although Harry was justifiably defending himself against Malfoy, who was about to cast the Cruciatus Curse, using an unknown spell was dangerous and reckless. However, despite this grievous action that could have permanently expelled him from Hogwarts, Snape only assigns Harry detention.
