In the books it is explained that the Elder wand didn't work because it was Draco who disarmed Dumbledore and not Snape. Thus Snape was not the owner of the wand even though he killed Dumbledor. Thus Voldy didn't become the owner when he killed Snape.
Rowling said in a 2007 PotterCast interview, “The Elder Wand knows no loyalty except to strength. So it's completely unsentimental. It will only go where the power is.”
The Elder Wand Carried a Set of Rules
No one saw this happen, so it was believed Snape had actually become the ruler, leading to Lord Voldemort killing him and thinking he had also earned it. But in reality, the rules held true and ensured Voldemort would fail because the wand was actually Malfoy's.
Why didn't Dumbledore tell Snape about the Elder Wand so Snape could break it before Voldemort found it? The answer is simple: It was far too risky for Severus Snape to be aware of both the Hallows and the Horcruxes.
He was playing him the entire time. So he wasn't going to tell him, even if he knew who the true master of the Elder Wand was. There's also no hints that Snape even knew who the Elder Wand's true master was.
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.
In order to conjure the avada kedavra curse, you have to want to kill your victim. We all know that Voldemort could easily kill a child without an ounce of remorse... but not Snape. Snape didn't want to kill Dumbledore, and this was why the spell was blue instead of the usual green.
Why was Draco the true owner of the Elder Wand? Voldemort thinks that he becomes the true owner of the Elder Wand by stealing it from Dumbledore's grave, but in the end we learn that the true owner was really Draco Malfoy, that is until Harry defeated him and allegiance transferred to Harry.
Voldemort told Snape he had been a faithful servant, but that he had to regrettably kill him, as he mistakenly believed he was the master of the Elder Wand, as Snape had killed Albus Dumbledore, its former owner the year prior, during the Battle of the Astronomy Tower.
Harry became so enamoured with the spell that he eventually used it to finish off Lord Voldemort. Here's how Harry's relationship with Expelliarmus became his signature – and why that's a good and bad thing.
A doe. And in his final battle with Lord Voldemort, Harry explained the significance of this to his adversary, and to us: 'Snape's Patronus was a doe,' said Harry, 'the same as my mother's, because he loved her for nearly all of his life, from the time when they were children'.
It is said that no spell can block the Avada Kedavra, so Dumbledore made statues physically block the spell for him.
He would always resent Harry for being James' son instead of his. Snape even said that he didn't want anyone to find out that he was protecting Lily's child, “especially Potter's son” (pg. 679 of Harry Potter and the Deathly Hallows) because of his hatred for James.
He finds out for sure immediately after Nagini's attack on Arthur Weasley. This night is significant in many ways. While Harry sleeps, he enters Nagini's mind.
In "Deathly Hallows," Snape also uses his Patronus to help Harry on his quest to find Voldemort's horcruxes; a Patronus charm can be used to send messages, and Harry seems to subconsciously recognize the doe as an extension of his mother, allowing him to trust it.
No. Snape had fully fooled Voldemort. Being the egomaniac that he was, he would have mentioned that he knew the truth as he killed Snape, instead he only mentioned that he was killing him to gain mastery of the Elder Wand.
We know the Elder Wand allied with Draco Malfoy, who disarmed rather than killed Albus Dumbledore. It later switched its loyalty to Harry Potter during his escape from Malfoy Manor. While deaths did occur in both situations (Dumbledore and Dobby respectively), neither Draco nor Harry committed the act.
The Elder Wand, the most powerful wand ever created, is one of three objects that make up the Deathly Hallows, including the Cloak of Invisibility and the Resurrection Stone. The Elder Wand was 15 inches long, formed by Death himself, made of elder wood, and contained the center of the tail-hair of Thestral.
Because he didn't believe disarming him would be enough. After Dumbledore was dead, Voldemort would have been told everything. Including the fact that Draco disarmed Dumbledore. But all he cared about was who KILLED Dumbledore.
Erroneously believing Snape is the master of the Elder Wand and that Snape's death will make him the master of the Wand, Voldemort kills Snape by having his pet snake Nagini bite him through the neck.
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.
Rowling previously revealed that Nagini is a Maledictus, which means she carries a blood curse that will doom her to transform permanently into a beast.
Yes, they did, as they both believed that Snape was a traitor and a murderer of their beloved friend and headmaster, Albus Dumbledore. Flitwick was angry and wanted to protect the students, but for McGonagall, it was more about revenge because Snape had killed her closest friend. They did want to kill him.