Ruby is the main villain in the series, we see hints of her throughout the first season but I'm planning on the arc involving her to be in the second season. We don't learn much of her until episode 26 which would be a prologue of season two, but an elongated trailer. She uses death magic and can rewrite how people die, when they die and where they die. Or at least, thats her curse. She became a very cynical woman after things happened to her, so after awhile of hurting she used it to her benefits and with her curse and her learning necromancy magic, she became known as the Goddess of Death and earned the nickname Hel.