RPF
      +--------
GNGJQ | JULGXJR
       -GNGJQ
        =====
        HNFYFJ
       -RWGMXQ
        ======
         LLYPWR
        -LNUJNQ
         ======
          RMQXL

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: hard
missing: T