PEPR
      +---------
PPPTM | PQLPFERM
       -PPPTM
        =====
         ERQLE
        -EERXH
         =====
          PLXFR
         -PPPTM
          =====
           WWXHM
          -RRXWU
           =====
           PJXMF

base: 13
letters: EFHJLMPQRTUWX
difficulty: medium
missing: J