Infinite Ring Genjutsu

This extremely powerful illusion, a creation of Hyouya's Kuzu-no-Ha spirit, causes the target to experience freefalling through a curving, colorless cavern, with extremely sharp spikes jutting out from the walls, which the user will try to avoid, by narrower and narrower margins. This technique cannot be broken by conventional means, and usually requires some unusual aid to be broken. While this technique is active, the user is bound to the spot, and will perceive any damage inflicted from the spikes as real. Long enough exposure to this technique will send the target into a coma.