Lamia

Marian Lamia (also known as Lamia) was a Greek demigod daughter of Hecate whose children were killed by Hera who later turned her into a monster due to her infidelity with Zeus. Lamia then used an incantation to allow all the monsters in the world to sense the taint of half-bloods, so that they could always be found. She did out of spite so that Hera would finally understand her pain of losing her children after so many demigods have died.

The Demigod Diaries
Son of Magic

Lamia is returned to life by Gaea who she sent to kill Alabaster Torrington, another child of Hecate. Alabaster tried to kill her several times but because Gaea has opened the Doors of Death, Lamia won't stay dead. While at a book store, she notices Howard Claymore and Alabaster interacting and pursues Claymore, only to discover later, he's an ally of Alabaster. She curses Claymore after their brief encounter, which shatters the protective magic Alabaster cast to shield himself from Lamia. But with Claymore's help, Alabaster discovers an incantation that will bind Lamia to the physical Earth, but their mother, Hecate steps in to intervene, saving both her children. According to Hecate, Lamia won't try attacking Alabaster again, knowing he could use that spell against her.