TTG
      +--------
XMRHQ | LFGRNJQ
       -LGNWR
        =====
         LQWHJ
        -LGNWR
         =====
          TGXLQ
         -YTJUN
          =====
           WUQH

base: 15
letters: FGHJLMNPQRTUWXY
difficulty: challenging
hints: R << W, N << R, Q << H
missing: P