Throughout the 1996-1997 school year, Draco Malfoy used the Imperius Curse on both Katie Bell and Rosmerta, and unsuccessfully attempted to torture Harry with the Cruciatus Curse, as he was severely injured by the Sectumsempra curse casted by Harry.
Draco tried to use the crucio curse, a curse that if you use you end up in prison for life, Harry Potter got scared and seeing Draco as an enemy he used a special magic to stop him, Snape then punished Harry by not letting him participate in quidditch and making them do manual labor with a ban on using magic.
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.
During the Battle of Hogwarts, Voldemort used the Cruciatus Curse on what he believed to be Harry Potter's dead body as a way of dishonouring it and to show he had won. Harry felt no pain because the wand Voldemort used, the Elder Wand, refused to harm its true master.
How Did Harry Use CRUCIO? (Harry’s DARKEST Book Moment NOT Shown in Movies) - Harry Potter Explained
Why didn t Bellatrix feel Crucio?
For example, despite being furious with Bellatrix Lestrange for her murder of his godfather in 1996, Harry Potter was only able to cause her a brief moment of pain with the Cruciatus Curse because he used it out of "righteous anger", though he was still able to knock her off of her feet with it.
Nevertheless, while the impact of Avada Kedavra was unforgettable, Crucio was far more deadly than that, and Imperio as it could make a victim beg for death solely to stop the pain.
In the films, Sectumsempra appears as a small flash of white light which causes a cut when it strikes the target. In LEGO Harry Potter: Years 5-7, Harry uses Sectumsempra on Malfoy only to find out the spell has, apparently, painlessly sliced him in half.
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.
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.
Dolores, though, wrongly believes him to be attempting to speak to Dumbledore - who is wanted by the Ministry of Magic for treason. In order to coax information from Harry, Umbridge demonstrates a willingness to use the Cruciatus Curse to 'loosen his tongue'.
Throughout the 1996–1997 school year, Draco Malfoy would go to the washroom to find company with Moaning Myrtle, confiding the stress of his mission and fear of failing it.
After the Wizards' Council was reformed into the Ministry of Magic, tighter restrictions were placed on the use of certain kinds of magic. The Imperius Curse was deemed by the Ministry to be Dark magic, and, along with the Cruciatus and Killing Curses, were declared "unforgivable" in 1717.
It's safe to assume that Draco's hatred of Harry was fueled by jealousy. Although Draco attempted to disguise his jealousy with confidence, it still makes an appearance throughout the franchise.
Although it is not confirmed to have been the Killing Curse, it is highly likely that Ron attempted to kill Voldemort's snake, and last Horcrux, Nagini, with Avada Kedavra. This is because, in the movies, Ron can be seen firing out a green spell at the snake, and it looks just like the Killing Curse.
Lord Voldemort charged Draco with making up for Lucius's failure, and he became a Death Eater at age sixteen but was quickly disillusioned with the lifestyle.
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.
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.
Effect. Unforgivable Curses are the three most powerful and sinister spells known to the wizarding world, and are tools of the Dark Arts. They were first classified as "Unforgivable" in 1717. They are the Killing Curse, Avada Kedavra, the Cruciatus Curse, Crucio, and the Imperius Curse, Imperio.
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.
Draco spots Harry and pulls out his wand. 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.
The book and the films diverged. In the book he is not hit with the killing curse. I believe in the movie he is. In the book, the curse that hits Sirius is not identified (although it is rumoured to be Stupefy because of the red light), and him being knocked through the Veil is what causes his death.
The incantation for the curse is “crucio.” Created in the early Middle Ages by dark witches or wizards, the Cruciatus Curse was initially made for torture, though was an effective tool in duels as well.
