VWXV
      +---------
NWNJX | TMNVJJMN
       -NWNJX
        =====
        PJQYUJ
       -PZPZQL
        ======
         HRMRJM
        -HUHRTZ
         ======
           RQXXN
          -NWNJX
           =====
           NYWZW

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