Who is Ereshkigal from Myths from Mesopotamia: Creation, the Flood, Gilgamesh, and Others and what is their importance?

Ereshkigal is the mistress of the Underworld. She is the daughter of Anu, sister of Ishtar, and wife to Nergal. She is also Ninazu's mother. When Ereshkigal attempts to kill her sister, she changes her mind after her father sends a man to trick her. She also attempts to kill her husband after he successfully escapes the Underworld, only to marry him when he returns.