After learning how Victor Creel was able to evade death back in 1959, Robin and Nancy deduce that playing the victim's favorite song can help them escape the trance that Vecna places them in, with music and happy memories being the only way to keep Vecna's fatal curse at bay.
During the episode, Nancy and Robin learn that music is the only thing that can save people from Vecna's wrath. This bit of information proves useful as the gang is able to fend of the upside down demon and save Max using her favorite song Kate Bush's 1985 hit "Running Up That Hill (A Deal with God)."
If Vecna has you in a trance, listening to your favorite song can help pull you out of it, as we saw when Vecna attacked Max only for her friends to pull her out his trance using the synth-tastic stylings of Kate Bush, specifically her 1985 hit “Running Up That Hill (A Deal with God).”
Under the control of Vecna, Max levitates into the air. That's why, for the fictional character of Max on Stranger Things, her emotional connection to Kate Bush's song was able to save her from Vecna.
He killed three teenagers from Hawkins and then set out to take Max from the gang. In a genius move, Dustin began playing Max favourite song, Runnning Up That Hill by Kate Bush. Listening to that managed to bring Max out of the Upside Down and out of Vecna's reach.
The Stranger Things official Twitter account shared the news. "Wanna know what songs would save YOU from Vecna? Head to your Upside Down Playlist on @Spotify to find out... the first song on the list = your saviour song," a post read.
When Dustin and the gang pop Kate Bush's 1985 hit "Running Up That Hill (A Deal with God)" into Max's cassette player. It's her favorite song that allows her to escape the Upside Down and break out of Vecna's clutches.
So, Max was nearly murdered like Vecna's three previous victims. Just before Max died, Eleven rallied her strength, defeated Vecna and freed Max -- but the damage had already been done. Even though Max was free from Vecna, she died in Lucas' arms.
Patrick was targeted due to his father's abuse of him. Finally, Vecna targets Max for her trauma from witnessing Billy's death and uses Barb's (Shannon Purser) death as a way to use Nancy.
She breaks free, momentarily incapacitates Vecna, and runs with the determination to live toward her friends, dodging debris that Vecna throws in her path. Max hurls herself through the portal, awakes from the trance, and is held by Lucas (Caleb McLaughlin).
As Vecna, he uses these mental abilities as a way to psychologically weaken and lure in his victims – much in a way that Pennywise, Freddie Kruger, and Pinhead do. (All of which have been cited by show creators the Duffer brothers as inspirations for the villain.) But he does have a surprising weakness: music.
These visions build over time, and within a space of 24 hours Vecna's victims enter one final trance. There, Vecna taunts them, rejoicing in their heartache and sorrow, before killing them. Vecna's victims die in an agonizing way, lifted high into the air.
Ultimately, it is revealed in Stranger Things season 4's finale that the reason why Vecna was killing Hawkins teenagers was to create a massive gate that merges the Right Side Up with the Upside Down - and he specifically needed four bodies to do so.
Stranger Things' season 4 introduced the vicious Vecna, who kills people by infiltrating their minds and killing them from the inside. He can be stopped, however, if his victim listens to their favorite song.
After a certain period of time, Vecna will finally kill the victim by placing them into a comatose-like state, in which they will be unable to respond to outside stimuli.
She is suffering, but instead of giving in she chooses to fight and, more importantly, to keep fighting. “Dear Billy” is a phenomenal episode and in the moment has an air of finality. Max has escaped Vecna, so she is safe from Vecna.
Vecna feeds off his victims' trauma and haunts them with their own darkest thoughts.
Vecna lives in the Upside Down and preys on people's past traumas and guilt. The monster curses its victims, making them relive their trauma in progressively more gruesome ways until it violently kills them.
Eleven has a memory during this episode and realizes that 001/Henry Creel (Jamie Campbell Bower) wants her to join him on his evil journey, and she banished him to the Upside Down. 001 then transformed into Vecna, the horrifying Stranger Things villain.
After serving as bait for Vecna, she becomes his “final sacrifice,” getting her bones broken and losing her vision during a low point.
At his empire's height, Vecna was betrayed and destroyed by his most trusted lieutenant, a vampire called Kas the Bloody-Handed, using a magical sword that Vecna himself had crafted for him, now known as the Sword of Kas.
Is Max alive at the end of Season 4? Physically, yes. Lucas tells his friends that Max is in a coma, and we see her wearing casts on her arms and legs. The Duffer brothers have also confirmed that at the end of Season 4, Max is alive yet "brain dead, blind, and all of her bones are broken."
So the gang hatches a complex plan to bait Vecna with Max, while Nancy, Steve (Joe Keery), Robin (Maya Hawke), Eddie (Joseph Quinn), and Dustin (Gaten Matarazzo) go into the Upside Down to kill Vecna while he's “weak.” The good news is Eleven (Millie Bobby Brown) has figured out a way to help from across the country ...
On top of that, Will Byers confirms that Vecna is, in fact, alive. Byers has a deep connection with Upside Down, so he can always sense the existence of Mind Flayer or Vecna. After returning to Hawkins, Will can sense that Vecna is injured and in pain, but the demon from Upside Down isn't dead.
Will Byers' favorite song isn't hard to pick out, either; in the first season of the show, his older brother Jonathan introduces him to “Should I Stay or Should I Go” by The Clash. Later, when he's trapped in the Upside Down, Will listens to the song to keep himself calm.