Vial of Shadow Tendrils

A small vial filled with thick, pitch-black liquid. From the substance inside small tendrils form, worming around passively. The tendrils react to the presence of void. This includes areas of the void as well as materials or artifacts originating from it. The substance can locate such sources of void within a range of 100 miles. When this happens, the closer the vial is brought to the source, the more aggressively the liquid tendrils will behave, gravitating to the direction of the source. When the void source is far away, the tendrils point only in a very general direction. The liquid only resonates with pieces of the void that are on the same plane of existence as it.