MGTT
      +---------
YVHJW | TXZQHLJM
       -YVHJW
        =====
         UNGZL
        -UMWHR
         =====
          RQNHJ
         -RHPVY
          =====
           JJJXM
          -RHPVY
           =====
           MGRNZ

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: hard