QNT
      +--------
QRTFQ | RHYHUTN
       -XRXGL
        =====
        WHFGRT
       -HJRPXY
        ======
         QFFQNN
        -QYTJJL
         ======
          QXPLT

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