The world boss closest to them was a super mutant, which was originally an unknown aquatic creature that had undergone an extreme radiation mutation. After constantly devouring other monsters, it eventually turned into a super mutant asserting its dominance in what was once a city but had now been transformed by its immense strength into a swampy water region.
When Lin Xiao and his group arrived, they could still vaguely make out the remnants of buildings in the swamp, and even see a statue in the center of the city that had not completely submerged, as well as a colossal creature not far away with an indescribable appearance, sporting six heads and countless tentacles, some a kilometer long, some several kilometers, writhing and coiling in the center of the city.