Complex sentence: Nabu was the god of writing and scribes, taking over the role from the Sumerian goddess Nisaba, and was the keeper of the Tablets of Destiny which recorded the fate of mankind and allowed him to increase or diminish the length of human life.
Split into simpler sentences: Nabu was the god of writing and scribes, taking over the role from the Sumerian goddess Nisaba. He was also the keeper of the Tablets of Destiny, which recorded the fate of mankind and allowed him to increase or diminish the length of human life.