Complex sentence: The others stay in the ruins of Sanctraphrax and build the city again as it always should have been, and when the city is restored they will bring back its population, and the new Phraxdocks, which are located where Old Undertown used to be.
Split into simpler sentences: The others stay in the ruins of Sanctaphrax and build the city again as it always should have been. When the city is restored they will bring back its population, and the new Phraxdocks, which are located where Old Undertown used to be.