Bury Our Bones in the Midnight Soil

by V.E. Schwab

but she finds herself hooking the gold chain with her fingers and drawing the pendant from beneath her hoodie. The pendant, which isn’t a pendant but a locket, a vial. Her little piece of home. A bit of glaur, Catty called it—dirt, but not just any dirt. Her mother’s, taken from the grave, a gift from Eloise on that blue-tinted wedding day. She unscrews the hidden lid and tips the smallest bit into her palm, and the moment it touches her bare skin she is back in the cemetery plot, and all the strength is rushing out of her, the life leeching backward, her limbs shriveling and her heart drying up and— Alice recoils, wrenching her hand back so fast the flecks of grave dirt rain down onto the splintered marble.

Oh yeah this is how she kills sabine