Mortal Kombat 9 Walkthrough Challenge Tower Strategy Guide for the XBOX 360, PS3. The MK Challenge Tower consist of 300 challenges. Once you have successfully completed each challenge you will be rewarded with koins for you to unlock Krypts, which are located in the extras menu. The krypt contain finishing moves, artwork, old school charters and much more. Some of this challenges can be easy but some can be straight out challenging and that where we come to the rescue.