This scenario requires you to obtain a Key to the Palace of Lei Shen and queue at Taoshi.
This scenario is, for all intents and purposes, removed from the game. It is no longer possible to obtain Key to the Palace of Lei Shen, so once you've run out of your stockpile of these keys, that's it. Feel free to express your feelings on this - and the atrocious 2-week advance warning that it and its associated achievement was going away - in the official stickied forum thread.
This scenario takes place (lore/location-wise) in the "Royal Amphitheatre" section of the new 5.2 raid, Throne of Thunder.