According to Harry Potter series author J.K. Rowling in a 2007 live chat with Bloomsbury.com, Harry lost his ability to speak parseltongue after ... Yes, he loses his ability to speak Parseltongue. In fact he lost the ability the moment Voldemort destroyed his part of his soul which lived as a horcrux ...
After Lord Voldemort destroyed the fragment of his soul residing in Harry, Harry seemingly lost the ability to speak Parseltongue, about which he was glad and relieved. Over the next twenty-two years, he never attempted to speak the language, presuming that it had died with Voldemort.
Moreover, J.K. Rowling said that Harry would not have continued to use his ability to communicate with snakes as an adult in an interview with Today.com. She stated that Harry would not be able to utilise Parseltongue in his adult life because it is a language that is only suitable for speaking with snakes.
The only change to Harry was that he no longer had a connection to Voldemort. That means he could no longer detect his presence, read his mind, or speak Parseltongue.
If you want to call their mind connection a power (of any level or sort), then it was lost once Voldemort died. He did lose the ability of speaking Parseltongue when Voldemort was defeated but regained the power in The Cursed Child because of Delphini aka Delphi, Voldemort's daughter.
Albus Percival Wulfric Brian Dumbledore was the only wizard Voldemort ever feared and the only one who could have defeated him in a duel. Albus Dumbledore is the most powerful wizard in the Harry Potter.
Defeating The Dark Lord with his signature spell
Disarming is about defence, not murder. Voldemort was a killer, Harry was not. It was an important distinction for Harry, who had learned so much about Voldemort and seen first-hand the ways in which they were similar.
Voldemort intentionally made six Horcruxes, but when he used Avada Kedavra on Harry, he unintentionally created a seventh Horcrux. Instead of dying, Lily's love for Harry created a counter 'curse' known as Sacrificial Protection and saved Harry.
The scar is no longer dark, and instead has faded almost to his usual skintone. Scars do fade with time, but J.K Rowling wrote in the book that: "The scar had not pained Harry for nineteen years. All was well." Many people believe the fact the scar has gone dormant after he left Hogwarts is why it faded.
He became the Triwizard Champion and defeated multiple dark wizards and creatures before he was even 18 years old. Dumbledore himself observed Harry as the rare wizard whose ability to love and "pure" heart made him capable of defeating Voldemort.
Neither of them is Slytherin's heir. Although, as Dumbledore says, Harry's ability to speak Parseltongue is a skill accidentally transferred by Slytherin's actual heir, Voldemort, when he tried to kill Harry as a baby. So perhaps this is one myth with a bit of truth to it.
Professor Dumbledore could understand it
As J.K Rowling revealed, Albus Dumbledore had mastered Parseltongue too – although he could not speak it aloud. We're not sure why Albus learnt the language, but perhaps the Hogwarts headmaster wanted a better understanding of Voldemort.
Through his mother's family, he is the last descendant of the wizard Salazar Slytherin, one of the four founders of Hogwarts School of Witchcraft and Wizardry.
A rare language spoken by a small number of wizards allowing them to communicate with snakes, the ability to speak Parseltongue was usually inherited with the majority of speakers descended directly from Salazar Slytherin.
Salazar Slytherin and his descendants were fluent in Parseltongue — the ability to speak to serpents.
Salazar Slytherin was a descendant of Herpo the Foul, which is where he would have gotten his Parseltongue abilities. I believe Slytherin was the first “famous” descendant of Herpo, so he would be one of the first Parselmouths we'd know of since this ability wasn't widespread at that point in Wizarding history.
However, becoming immortal from gathering the three was a misconception, as being a true Master of Death was realising and accepting the fact that everyone would die and there were worse things than death. Harry Potter collected the three Hallows and was willing to accept death and so became the Master of Death.
What's neat about the Harry Potter scar revelation is that it actually explains how it came to be. It's not just a random lightning bolt (which almost seems too basic for Rowling, in a sense). It's the sign for the very spell that Voldemort used to kill Harry's parents, resulting in the scar on his forehead.
The most likely reason why Lord Voldemort's nose disappeared and he devolved into such an evil-looking creature is that as he dabbled deeper into the Dark Arts, his appearance gradually became as distorted as what remained of his twisted soul.
Draco Malfoy's mother Narcissa was cold, cunning and devoted to the Dark Lord. But she was also a mother, which meant she was willing to risk everything to make sure her son was safe. When Harry survived Voldemort's Killing Curse for the second time, Narcissa pretended he was dead so she could get to Draco.
Though Harry encountered many opportunities that deemed Avada Kedavra necessary, it remains as one of the Unforgivable Curses Harry Potter never cast. For one, he viewed the spell as an immoral practice commonly used by users of the Dark Arts.
The Death Eaters and the Dark Lord don't simply cast Avada Kedavra on everyone all the time because it doesn't suit their long-term goal of ruling the world and having a wizard-run society.
8 Hermione Granger: Alohomora
If there is a spell to encapsulate the asset Hermione is to everyone's favorite magical trio, it has to be Alohomora. Alohomora is, fittingly, the spell that is used to unlock locks.
Avada Kedavra
It's used to kill people, it's an Unforgivable Curse, and it was Voldemort's favourite, so it's going last. There's probably a big philosophical debate we could get into about violent curses like this – would this one have been okay to use on an evil dark wizard, for instance?