Tonton Streaming Carmilla (2014) S1E32 - Mommy Dearest

Possessed by The Dean via an evil necklace, Carmilla's "mother" shows up embodied in Laura, striking to make a deal with her "daughter" about not threatening the cultish sacrifice under any circumstances. While she's at it, she destroys the flash drive on which J-P was saved, and let Will take Kirsch hostage as the last victim instead of Laura herself.