Multi-Headed Siren

Just a random monster I created, loosely inspired by the traditional long-necked woman spector from Japanese legend. It can grow as many heads as it wants, or just grow one head, and change its body, allowing it to change into any type of woman it wants. It can also sense a man's desires, allowing it to take the form of whatever type of woman a man wants. I figure it would do something bad to the guy after he's been lured in, but I haven't thought of what. She could maybe steal the man's life force, or something like that, but hopefully I can think of something new...