The accumulative “forever and ever” indicates the intensity and severity of the judgment the Lord has inflicted on Babylon (Genesis 19:28; Isaiah 34:10). We may also hear in the prolonged element of her burning the fact that “Babylon” is not a once-off occurrence (say, at the end of time) but is a mindset that appears repeatedly in the course of history, yet always falls and is destroyed. So there is repeated incentive to praise our God.
3 Once more they cried out, “Hallelujah! The smoke from her goes up forever and ever.”