He could have easily defeated Malfoy outright when he showed up, or even after losing his wand. But that wasn't the plan. He needed Malfoy to get the wand so Harry could take it from him. It would have been convenient for Malfoy to kill him, too, but he know Malfoy wasn't brave enough for such an act.
We saw above that his confrontation with Dumbledore must indeed have been traumatic, as Dumbledore offered to protect both him and his mother from Voldemort's wrath and Draco was unable to kill an already dying and wandless wizard. Dumbledore's offer of refuge is exceedingly important to the Draco redemption theory.
Dumbledore may have been a legendary wizard, but he can't be compared to, well, Merlin, a wizard so legendary even Muggles know of his exploits. Merlin was the world's most famous wizard, and, arguably, the world's most powerful.
Likely not. He was ill from his cursed hand, which was killing him slowly, as well as the potion he drank. Unless you think he was feigning his weakness to Harry before they returned to Hogwarts, Dumbledore was in no condition for a fight, least of all against several opponents, most of whom were seasoned killers.
However, Draco was ordered by Voldemort to kill Dumbledore. Lestrange saw this as an opportunity to test Snape's loyalty and while making this vow to always watch over Draco, Lestrange forced Snape to agree to killing Dumbledore himself in case the youngster was unable to do so.
So, Voldemort had to kill Snape for the wand's allegiance to switch. Voldemort knew he couldn't cast Avada Kedavra with the Elder Wand to kill its master, so he ordered Nagini to be the one who killed Snape. In reality, the Elder Wand belonged to Draco, as he was the one to disarm Dumbledore in the Astronomy Tower.
Bellatrix Lestrange (née Black) is the first female Death Eater introduced in the books. Aunt of Draco Malfoy and Nymphadora Tonks. She was introduced in Harry Potter and the Order of the Phoenix. She is the most faithful member of Voldemort's inner circle.
While Dumbledore is a powerful wizard, Gandalf's innate magical abilities and experience in leadership and diplomacy give him an edge in a battle between the two. While the outcome of a battle between the two would depend on the circumstances, Gandalf would win more often than not.
Dumbledore is extremely powerful even in his weakened state he could easily defeat Bellatrix no matter how wicked or evil Bellatrix is acting. Bellatrix would run away the second she sees Dumbledore and if she was tempted to fight she would be destroyed in under a second.
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.
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.
Draco had several reasons for lying to Bellatrix, including the fact that he was never a bad person. Moreover, he no longer found working for the Dark Lord appealing and hated how Voldemort treated his family. He did not intend to harm anyone and believed Harry was the only person capable of defeating Voldemort.
Lord Voldemort (Ralph Fiennes), aka Tom Riddle, was described by Dumbledore as one of the best students ever to graduate Hogwarts as well as "the most dangerous Dark wizard of all time." Before he had even learned about the existence of the Wizarding world, he was terrorizing his fellow orphans with impressive but ...
Winner: Snape
The kind of versatility in magical abilities that Snape displayed was almost around the level of Albus Dumbledore and Voldemort, making him easily more powerful than the average wizard and even the members of the Order of the Phoenix and the Death Eaters.
Peter Pettigrew
He definitely ranks at the top of those who should be regarded as the most evil members of the Death Eaters, if for no other reason than that he was more than willing to betray Lily and James to their certain deaths at Voldemort's hands.
Speak to Sebastian in the Undercroft after this and he'll teach you any Unforgivable Curses you have missed up to that point, including Avada Kedavra. It's worth learning the curse as doing so should have no negative outcome on the game's story.
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.
Avada Kedavra, also known as the Killing Curse, kills a person instantaneously and without injury. There is few counter for it, and only one person, Harry Potter, has ever survived it with Sacrificial Protection that has been endowed upon Harry Potter by His Mother Love for Him.
At one point, Snape is named as a Death Eater by Igor Karkaroff, but Dumbledore comes to Snape's defence, claiming that although Snape had indeed been a Death Eater, he changed sides before Voldemort's downfall and turned spy against him.
Knowing that Snape has been on the Dumbledore's side for all seven of the Harry Potter books reveals him as an extremely brave man and a truly skilled spy. Snape has had to face and deceive the terrifying Lord Voldemort constantly.
Following Voldemort's fall, Snape never attempted to find his old master, having switched sides ever since the Dark Lord had targeted Lily and this allowed him to avoid time in Azkaban as Dumbledore staunchly defended him.