Ghost boundaries wouldn't last forever. A smart Phantom Demon would plan out when and where to place down their ghost boundaries to maintain an uninterrupted flow of crowd control on the battlefield.
But right now, Qiao Yifan's One Inch Ash was placing down ghost boundaries one after the other. Dark Boundary, Ice Boundary, Silence Boundary. All of these were ghost boundaries with powerful crowd control. Usually, these boundaries would be linked together such that the opponent would always be under the effects of one of them. However, Qiao Yifan had set all three down on top of each other to completely seal off Sun Xiang and Jiang Botao. One Inch Ash was even in the midst of casting a fourth ghost boundary.