On From Dusk Till Dawn Season 3 Episode 7, Sex Machine uncovers a cult that worships Amaru. They sacrifice culebras to Amaru's soul gatherer. When Sex Machine tells Seth about this, Seth thinks this can be their lucky break.
Sure enough, when the team goes undercover at the cult's next sacrifice, Amaru shows up, and they are able to grab her. They take her back to Burt's gas station, where he just happens to have a pen capable of holding a Xibalban. Burt is always prepared.
Sex Machine and Seth being an exorcism, hoping to expel Amaru from Kate's body. Meanwhile, the rest of the team realizes that they are not alone. La Llorona has come for Amaru, and unfortunately for the team, she hates men.
When la Llorona scratches you, her venom makes you relive all of your worst memories. There's also seizures, so basically it's a lot of fun. She manages to infect Freddie and Scott.
Richie has learned that ever since being possessed by Amaru, he can tap into the Xibalban frequency. He heard Amaru's distress call to la Llorona, and he even heard why la Llorona was really there - to find out where Billie and Margaret are.
Amaru is trying to complete the purification ritual that she attempted to perform in Shady Glen. It requires a mother and child. Richie, Freddie, and Burt get to Margaret and Billie too late. They've already been taken, but at least they kill la Llorona.
Meanwhile, the exorcism succeeds, temporarily. Kate comes back and warns Seth that this was all a trap. She also tells him that Amaru is too powerful to be defeated, but Seth urges her to keep fighting. When he apologizes to her, Kate says she doesn't forgive him.
Scott, under the influence of la Llorona's venom, frees Amaru.