HZM
      +--------
PXRNR | WJLGHQN
       -NJQVP
        =====
        LYTPXQ
       -LJMYNT
        ======
         HPQPNN
        -HHZRVZ
         ======
          LXRZV

base: 16
letters: GHJLMNPQRTUVWXYZ
difficulty: challenging
attributes: long, meticulous
missing: U