The Wandavision finale introduced a lot of new concepts that will have lasting ramifications on the Marvel Cinematic Universe, but perhaps none are bigger than the Darkhold, a famous magical tome that has long been a part of the Marvel Comic Universe and there's no better time than now to break down the book's origins alongside what this all-powerful spellbook can do. Wielded by Agnes, aka Agatha Harkness, it's clear that the book is not something to be trifled with and will clearly make an appearance in the MCU following this latest story of Wanda Maximoff and the Vision.
The Darkhold itself first appeared in "Marvel Spotlight #4" in 1972, introducing the cursed tome as one of the most powerful tools in the supernatural world, for which Stephen Strange keeps under lock and key for some time. Originally created by the dark lord Cthon billions of years in the past, the book has insane abilities but is akin to the Evil Dead franchise's "Necronomicon Ex Mortis" and will normally have insanely adverse effects on its user. During one instance, Dr. Strange was forced to rely on the book while battling the legendary vampire king, Dracula, going so far as to completely eliminate vampires from the Marvel Universe for quite some time. Of course, as fans know, vampires would eventually return, giving Blade the Vampire Hunter plenty to do.
The book even spawned its own group of heroes in the Marvel Comics Universe, giving us the Darkhold Redeemers back in the 1990s. The band, which was introduced as part of Marvel's "Midnight Sons" line would travel around the world attempting to collect each page of the Darkhold, which was being used to twist the lives of those who came into possession of it. Crossing over with the likes of Ghost Rider, Blade, Dr. Strange, and various other Marvel supernatural beings, the team didn't last long but did make a dent in stopping the spread of evil that the book was leaving in its wake.
As fans who follow the Marvel Cinematic Universe know, this isn't the first time that we've seen the book make an appearance, as the fourth season of ABC's Agents of Shield focused on the arrival of the deadly tome, alongside the introduction of Robbie Reyes, the latest Ghost Rider, to the lore. While it's still unclear as to whether or not the events of the series are considered canon, it's clear that the Darkhold will have a role to play in Wanda's life moving forward.
Surprisingly, one of the biggest recent appearances of the Darkhold in the comics was its involvement in the life of Cletus Kassady, aka Carnage, who was attempting to use the book for his own nefarious ends. The book's location at present in the comics is unknown but with its inclusion in Wandavision, we definitely wouldn't be surprised to see it appear once again.