Dark Prison

Dark Prison first appeared in Deception

When knocked to the lower level, you could see prisoners in each of the 8 cells. The prisoners where unplayable characters, including Johnny Cage, Sonya, Mokap, Shang Tsung and every other non playable Deception character. (In MK Unchained, Frost, Jax and Kitana are not seen in the cells since they are playable)

The stage also had a stage fatality that was a spiked wall compressor that activated onces your opponent was knocked into it.

List of characters seen in the cells: Kintaro Sheeva Reiko Shang Tsung