This means that the killing curse (if I'm correct) has the power to destroy horcruxes. But when Ron and Hermione are about to die by Nagini, Ron casts the killing curse as a last resort and it simply rebounds off Nagini as it was nothing.
None of the good guys dare use the Killing Curse throughout the events of the movies and books, no matter how high the stakes and how difficult things are. But Ron Weasley is the exception, giving it a go in the Deathly Hallows: Part 2 movie when himself and Hermione look destined to die via Nagini.
In Harry Potter and the Deathly Hallows: Part 2, Harry uses the Blasting Curse against Nagini in an attempt to kill her and possibly to provoke Voldemort to chase Harry, so the snake would stay behind unprotected.
Cast by Hermione in Bathilda Bagshot's house when Nagini was coming for her and Harry; the spell ricocheted around the room, exploding a mirror and destroying Harry's holly and Phoenix-feather wand. She later referred to it as the Blasting Curse (DH17).
Cruciatus Curse ('Crucio')
Harry tried to use this spell himself. The first time was against Bellatrix after she had killed Sirius. His attempt was unsuccessful because, as Bellatrix mockingly explained: 'You need to really want to cause pain – to enjoy it – righteous anger won't hurt me for long…'
Harry makes use of two of the Unforgivable Curses in the books. Dueling with Bellatrix Lestrange, he attempts the Cruciatus curse, with limited results; Bellatrix says that he has to really hate someone to make the Unforgivable Curses work properly, righteous indignation isn't enough.
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.
Lord Voldemort and Nagini had a special relationship
So Nagini and Voldemort were definitely close. As a Parselmouth, (i.e. able to talk to snakes) Voldemort could communicate with her, and the pair often sent each other messages, even suggesting a telepathic connection at times.
Piertotum Locomotor | The Harry Potter Compendium | Fandom.
But when Ron and Hermione are about to die by Nagini, Ron casts the killing curse as a last resort and it simply rebounds off Nagini as it was nothing.
But now we know Nagini was no simple supervillainous pet, but a human woman cursed with the “Maledictus” blood curse, which, according to Rowling, is a female-only inherited condition which grants the affected individual the ability to transform into an animal at will, until one day, the transformation becomes ...
Nagini is revealed as one of Voldemort's horcruxes in "Harry Potter and the Deathly Hallows." Warner Bros.
The escaped boa constrictor in Philosopher's Stone wasn't Nagini. It was never Nagini.
Despite his knowledge of the Avada Kedavra incantation, Harry refused to use the Killing Curse. The three dangerous curses were classified as "Unforgivable" nearly 200 years before the events of the Harry Potter series.
A Gryffindor student and member of Dumbledore's Army, Lavender becomes Ron's girlfriend during the students' sixth year at Hogwarts, and soon becomes known around the Tower for what some would call very public displays of her affection.
Horcruxes can only be destroyed in specific circumstances that allow it's complete and utter destruction. In the movies, the horcruxes are destroyed in these ways: The killing curse — “Avada Kedavra.” Fiendfyre — a curse that creates powerful and magical flames.
Sectumsempra was a curse invented by Professor Severus Snape that lacerates the target and causes severe haemorrhaging. Snape created it as a student of Hogwarts, with the intention of using it against his enemies, likely including the Marauders, and it became one of his specialities.
Imperius Curse
It was one of the most powerful and scariest spells known to wizards. When cast rightly, the curse puts the victim under the caster's control, although a person with extraordinary willpower could resist it. It is known that Death Eaters use this curse in both Wizarding Wars.
Dumbledore's Forceful Spell. Albus Dumbledore's forceful spell is a spell of his own invention intended to reveal the number of times one's soul has been split and detached and possibly even the location of those split soul fragments. It's like a weird version of Homenum Revelio but – you know – for souls.
Nonetheless, despite her initially benevolent nature, Nagini's blood curse eventually turned her into a snake permanetly. Though it is unknown if she became evil as a result of that, or was turned evil as a result of Voldemort turning her into a Horcrux. As a snake, Nagini was completely loyal to Lord Voldemort.
Nagini is loyal to Voldemort because he can speak with snakes. As a Maledictus, there probably isn't much time after the events in The Crimes of Grindelwald before Nagini falls to her blood curse, becoming a snake forever.
When Harry and Hermione are on the first floor of Bathilda's house, Nagini (inside the corpse of Bathilda) tells Harry to "Come!" from the next room in Parseltongue. In reaction, Hermione jumps and clutches Harry's arm, and the two of them obey the command.
Avada Kedavra, also known as the Killing Curse, kills a person instantaneously and without injury. There is no countercurse for it, and only one person, Harry Potter, has ever survived it.