JQTQ
      +---------
JXRMJ | ZXPVQHPH
       -TWTTV
        =====
        JLNQYH
       -JPJXLZ
        ======
         PLTGMP
        -PGNRZM
         ======
          JPVWLH
         -JPJXLZ
          ======
            XTQM

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