Wattson's Fence Trap

Can someone please make Wattson's fences invisible to the naked eyes of other legends? But when enemis get close to her fences (like 1 metre) the fences is no longer invisible..

(similar to the virtual cage in arena when we get close its become visible)

By the time enemies enter the building through the door and realize ig, its already too late cuz they got trapped through the fences