After hearing that the Devil Horn Empire was attacking the Lantong World, Zhao Fu and his subordinates discussed whether they should attack the Devil Horn Empire. However, if they did that, they would at most only be able to stall the Devil Horn Empire, and Great Qin would not be able to benefit in any way. As such, it was best to attack the Dark Demon World while the Devil Horn Empire was attacking the Lantong World.
Now that the Devil Horn Empire was attacking the Lantong World, they naturally would not be able to stop Great Qin. That way, Great Qin would have three worlds.
Ever since the Grassi World, Half-Beast World, and Elf World had been conquered, the Dark Demon World had gone into high alert. Without the three worlds, they would not be able to stop Great Qin at all. As such, they would be the next world to be destroyed.
Moreover, Great Qin had already conquered a Continent in the Dark Demon World, and their world only had three Continents left.