On the season finale of Salem Season 2 Episode 13, Countess Marburg is remarking how lucky they are that the dark lord is now in their presence and how Salem will prosper. Countess Marburg tries to convince Mary to take part in celebrating this "glorious day," but Mary is not having any part of it. Mary no longer has a son and she can't be in the same room as the dark lord. After Mary leaves, the dark lord wakes up and demands Mary come back. After some convincing from Sebastian, she comes back in the room and, at first, she is reminded of the son she once had until he starts speaking about having her by his side as his wife, to which Mary leaves yet again.
The dark lord tells Countess Marburg he wants nothing to do with her and it's Mary who he desires. Even though the Countess is not happy about these circumstances, she goes out to retrieve Mary at the church. At the church, Countess Marburg isn't aware that she's being lured into a trap by Mary and Mary attempts to kill both of them in a fire. Mary is almost successful in her quest for revenge, but it stopped when Anne comes into the church and puts the fire out, saving Countess Marburg. Countess Marburg is now out for revenge and enlists Sebastian to do away with Mary once and for all because she doesn't deserve the dark lord. Sebastian takes Mary out into the woods, takes some of her blood and lets her go because he has unconditional love for Mary. Sebastian tells her where she can find John, if he's still alive, and sends her on her way.
Mary comes upon John's lifeless body and makes the ultimate sacrifice, giving her life for his.
Meanwhile, the dark lord takes revenge on Tituba by having her eyes clawed out by ravens and bites Mercy's finger off. Elsewhere, Cotton confronts Anne about her being a witch and when he tries to leave, she traps him into a room and takes complete control over him and his body.
In the end, Countess Marburg isn't able to keep her lie from the dark lord and, when he gets angry, he stabs her to death. Countess Marburg calls out for Sebastian to help her, but he declines helping her this time.
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