HGP
      +--------
WRFNX | PRXXJNF
       -WRFNX
        =====
        FQFFUN
       -NGLJRW
        ======
         MYUWXF
        -MYHPFY
         ======
           LLNT

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