MHHZN
      +----------
JQNGJ | WTMYRVNJT
       -JQNGJ
        =====
        MQXWZV
       -MHYXJH
        ======
         MZVXGN
        -MHYXJH
         ======
          HPLQQJ
         -HZRTHZ
          ======
           QHGMNT
          -HVLGVR
           ======
            ZXZYW

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard
missing: U