The Octo Garden (Octo-Garden) is a decadent and dangerous area in Outworld from Mortral Kombat 4. The picture of this scrapped arena can be found within the Krypt and Kontent gallery special features of Mortal Kombat: Deadly Alliance.
This age-old "garden" with octopus tentacle-shaped torches and skull ornaments is a forgotten and dangerous place found in a lake somewhere in Outworld, and it is surrounded by the realm's native squids that would clutch their tentacles onto anyone who falls off this arena. This garden might have been sometimes used as a place of sacrifice.
It was originally planned to have tentacles of octopi in this garden that would reach up from the water and wiggle around, but this background and even this entire arena never made it to the game, thus become a scrapped idea and only a picture remains.