The enclosed sewer system was an ideal hunting ground for those with extraordinary agility. For its prey trapped at the very core of it, it was nothing short of their worst nightmare.
Theoretically, there is no creature capable of maneuvering spatially in 3D based solely on footspeed.
Whether they were primates gripping tree branches and climbing, crawling creatures with claws and specialized skin that allowed them to scale walls and glass freely, or insects that could jump dozens of times their own height due to a hydraulic power output – they may be masters of 3D maneuvering, yet not one of them could realize a full-scale 3D movement, without any distinction between up, down, left, and right, in closed spaces.
Jumping power, grip, spatial perception and judgment.