Major spoilers for Season 2 of The Witcher follow.

Yes, Netflix’s The Witcher is adapted from author Andrzej Sapkowski’s The Witcher book series, but even fans who have read all of his novels and short stories can’t really predict what’s going to happen on the show since many plots from the books have been altered or further fleshed out to work better on the screen. The biggest surprise of the adaptation so far came in Season 2 with the introduction of Voleth Meir, an entirely new character who serves as a terrible threat to The Witcher’s heroes. Who is she? Where does she come from? Well, since monster-hunting witchers do intense research on their foes to know the best ways to defeat them, we’re doing that homework for you by providing everything you need to know about Voleth Meir, including her powers, origins and goals.

Where does Voleth Meir come from? During Netflix Geeked’s official The Witcher aftershow, The Witcher: Unlocked, showrunner Lauren Schmidt Hissrich explained that she and the show’s writers wanted a season-long villain for Season 2 who could provide the show with plenty of action and create plots that would unite its huge cast. Voleth Meir, also known as the Deathless Mother, delivers on both fronts. Many of Sapkowski’s creatures are inspired by folklore, and Schmidt Hissrich said Voleth Meir is based on the mythical witch Baba Yaga.

Stories of Baba Yaga are found throughout Eastern Europe. She appears as an old woman who lives in a hut that stands on chicken legs. In some stories, she helps those who encounter her in the forest, but other times she’s portrayed as a child-eating monster. That ambiguity is key to her portrayal in the show.

Twelve hundred years before the beginning of Season 1, a cataclysmic event called the Conjunction of the Spheres brought humans and monsters from different worlds to the Continent. One of those arrivals was Voleth Meir, and her power was so great that the first witchers, humans subjected to magical mutations to help them fight monsters, banded together to defeat her. They couldn’t actually kill her, so they entombed her inside her own hut. The witcher stronghold of Kaer Morhen maintains a tribute to Klef, one of the brave warriors who died fighting Voleth Meir after she stabbed him with his own dagger.

What are Voleth Meir’s powers? On the Continent, Voleth Meir appears as a wrinkled old woman with white hair and black clothes. Her hut can move on basilisk (a mythological reptile) legs, though it’s entombed beneath Elven ruins. Even trapped, she’s a formidable foe, able to read people’s minds to discover what they most fear and desire. She can communicate with people through dreams, taking forms she thinks will help her cause. For instance, she appears to Francesca in the guise of the elven prophet Ithlinne.

Voleth Meir is also capable of possessing people, trapping their minds in a dreamscape based on their desires so that they have to suffer to break free. While their minds are occupied, she has full control over her victim’s body and any special skills they possess.

The Deathless Mother is just one of seven members of the Wild Hunt, a fearsome group of incorporeal riders from another sphere that bring doom wherever they go. Now that she has been reunited with her fellows, their full power will pose a threat to everyone on the Continent.

What does Voleth Meir want? Voleth Meir waited a millennium for the chance to break free of her tomb and return to her home sphere. She preys on desperation and despair, and in Season 2 she’s able to create enough of it in the world to burst forth. She does this by manipulating the sorceress Fringilla, who wants the power to impress Emperor Emhyr of Nilfgaard; the elven leader Francesca, who wants a better future for her people; and the sorceress Yennefer of Vengerberg, who loses her power after using too much magic and wants it back.

In “Kaer Morhen,” the second episode of Season 2, Voleth Meir offers all three women what their hearts most desire. She appears in their dreams to lure them to her tomb, where she encourages Francesca and Fringilla to form an alliance. Yennefer rightly doesn’t trust the witch, who mocks Yennefer, saying, “I’m going to let you bake some more. I want your desperation crisp.” Every time Yennefer struggles and feels powerless throughout the season, Voleth Meir appears to her, offering a chance to get her magic back. Yennefer finally makes a deal, in Episode 5, “Turn Your Back.” Voleth Meir tells Yennefer she needs to kidnap a girl she describes as “a key.”

But the witch’s bargains are all poisonous. Other Nilfgaardian leaders don’t accept Francesca and Fringilla’s plan to provide the elves, who’ve been pushed out of their lands by humans, safety and a new home in exchange for their military assistance. In Episode 6, “Dear Friend…,” Yennefer discovers that the unknown girl is actually Princess Cirilla of Cintra, Geralt of Rivia’s adopted daughter. While Yennefer might not admit it, she loves Geralt but she is so desperate to regain her magical strength that she betrays Geralt and Ciri anyway and takes her away from the witcher. Episode 7 was appropriately named “Voleth Meir,” as it marks the witch’s plans coming to fruition. Fringilla murders many of Nilfgaard’s generals to avoid being usurped, but Francesca’s newborn baby is killed.

At the end of that episode, the pain and suffering all those actions create finally gives Voleth Meir the power she needs to escape her prison, possess Ciri, and pursue her vengeance against the witchers. In the Season 2 finale she kills many witchers while they sleep, using Klef’s dagger taken from the stronghold. She also uses Ciri’s power against them by summoning horrible monsters from other spheres. As we see in the season finale, the witchers are still incapable of killing Voleth Meir, and she’s able to escape to her home sphere.

The most dangerous thing about Voleth Meir is that people don’t understand her true motives and powers and believe that she can help them achieve their own desires. If she tells you she’ll give you an early look at Season 3 of The Witcher, don’t believe her. Now you know better than to negotiate with someone you find buried in an ancient tomb.