Maddening Oubliette

The target is transported to a dark and dank prison in some unspecified horrific demiplane, where tentacles writhe around, clawed fingers grab at the creature (though they deal no damage), and harsh, whispering voices speak blasphemies and maddening secrets. At the end of each round within this terrifying oubliette, the target can attempt a Will saving throw in order to escape the prison. The saving throw has a penalty equal to the number of rounds the target has spent in the oubliette (minimum -1 and maximum -5). If the target succeeds at its saving throw, it returns to its former space. If that space is occupied or otherwise unavailable, the target is shunted to the nearest available space. When the target returns from the oubliette, it is confused for a number of rounds equal to the number of rounds of imprisonment (minimum 1), unless it was confined in the oubliette for 10 or more rounds, in which case the target is affected as if it were subject to an insanity spell instead.