A little bit of mystery mixed with the impossible.
http://www.nintendoworldreport.com/news/32844
New Super Mario Bros. 2 is receiving its last two Coin Rush DLC packs soon. Mysterious Adventure Pack and Impossible Pack have been revealed in a video by IGN. Both packs will be made available December 20.
Mysterious Adventure takes the hidden paths known to Mario fans and runs wild with the idea, revealing coins with each path discovered. The Impossible Pack seems akin to the Nerve-Wrack Pack released previously, and pits Mario against the hardest of trials. Mysterious Adventure is rated as three out of five stars for difficulty, with a target of 20,000 coins, while Impossible carries a difficulty rating of DANGER!, with a coin target of just 100.
Coin Rush DLC can be downloaded through the shop area of NSMB2's Coin Rush Mode. Previous packs sold for $2.50 each