In the final episode of season four, one of the core characters, Max, falls victim to Vecna's curse. She's left lifeless, with her arms and legs broken and her eyes clouded by thick cataracts. Some of her final words are, “I can't feel or see anything,” leading viewers to believe that she's blind.
In Stranger Things' "The Massacre at Hawkins Lab," Vecna/001 clarifies that the massacre victims are "not gone" and are "still with [him]." Considering Brenner's clarification that Vecna consumes his victims, Vecna stores his victims' essences in his Mindscape for further use.
In the real world, he makes the victim levitate while in their trance, before snapping their bones and neck, and crushing their eyes. The murder site then becomes a small gate into the Upside Down, as part of a long term goal to apparently bleed both dimensions into one.
Vecna's powers allow him to form psychic connections with people in reality, especially teenagers dealing with trauma and mental health issues. Vecna develops these connections with young and vulnerable teens so that he can get out of the Upside Down and gain access to the real world by opening four gates or portals.
Once he takes control of the mind, he traumatizes them by showing the visions of their dark past. He takes them to unknown places and gives them a glimpse of himself. The pain of his victims doesn't end here. Every single one of his victims experiences nose bleeding and severe headaches as well.
Clocks represent a passing of time, which can represent the fact that Vecna's victims' time has nearly run out — it is no coincidence that many of the clocks are set to midnight. Throughout the series, we learn that Vecna is a human who found himself trapped in the Upside Down for years thanks to our girl, Eleven.
Played by Jamie Campbell Bower, each prosthetic was glued to his skin with medical adhesive by prosthetics designer Barrie Gower and his team. For the finishing touch, Vecna was covered in "glossy slime to make him really, really glossy and wet looking," according to Gower.
(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.
And while his usual modus operandi is to embody his victims' negative self-talk (another very real psychological phenomenon), this time he is telling Nancy his plans and then releasing her so she can report back to everybody—Eleven included—that the end is nigh, with the goal of discouraging and disempowering them.
In the visions of her trauma induced by Vecna, Chrissy's mother appeared both mentally and emotionally abusive towards her daughter - and it's implied her comments about Chrissy's figure caused her daughter to develop her eating disorder.
Hawkins has suffered a lot of trauma over the years - not all of which is connected to Hawkins Lab and the Upside Down - and Vecna's curse takes advantage of that. Vecna appears to carefully choose people who feel a strong sense of guilt or shame, particularly if those emotions are repressed.
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. (And we mean, like, really violently.)
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.
Max's past experience with trauma — namely, watching the Mind Flayer brutally kill her stepbrother Billy (Dacre Montgomery) in Season 3 — makes her a target for Vecna's manipulation.
At the same time, Nancy, Steve and Robin reach Vecna's body in the Upside Down and throw multiple Molotov cocktails at him before Nancy shoots him, sending his blazing body flying out the window of the Upside Down's Creel House.
While falling into the dark dimension, One/Henry is struck by lightning, disfiguring him.
What is the significance of 4 for Vecna? The new season shows that the four chimes of the grandfather clock symbolize the four victims Vecna needs to claim in order to enter our dimension and take over humanity.
Since her limbs were still broken and she's now comatose, it seems Max will still be blind after Stranger Things' season 5 time-jump, as Vecna had already “taken her eyes.”
The theory predicts that Vecna wants to regain his human form, and he will use Will to do so in Season 5. Knowing that Vecna singled out Will in Season 1, it's a reasonable theory, but it might go too far. After all, Vecna already has a human form, and he has vowed to eliminate humanity.
Season 4's main villain Vecna contains a multitude of easter eggs. To start, he has a giant, claw-like left hand. This is a reference to the D&D character Vecna, for whom this Vecna is named; the D&D Vecna has a monstrous hand infused with dark magic.
His first victim was Chrissy Cunningham. Vecna targeted Chrissy by using her depression and eating disorder against her in his visions. Chrissy was killed in Eddie Munson's trailer, and the first gate was opened on the ceiling.
This is because his trusted accomplice, Kas the Bloody-Handed, betrayed him and used the sword Vecna created himself to chop off his left hand and remove his left eye. This ultimately destroyed Vecna. Though they're clouded with cataracts, Vecna in Stranger Things has both of his eyes. For now, at least.
Jamie Campbell Bower wore a costume and prosthetics to transform into Vecna in "Stranger Things." The actor said that his suit had a "flap" that went over his crotch.
One of the most important sequences in this episode featured Vecna showing Nancy the real circumstances of the “eyeball murders” in the 1950s, with flashbacks indicating that young Henry Creel murdered his family when his mother tried to get him psychological help and he intentionally framed his father Victor for the ...
In episode 7, Vecna is revealed to be Henry Creel (played as a youngster by Raphael Luce), the son of Victor Creel (Robert Englund) and his wife Virginia (Tyner Rushing) shown in the 1950s flashbacks.