????????
      +---------
UQXTP | LULUXXEL
       -UQXTP
        =====
        EGNEEX
       -EUNNXR
        ======
         TNEJLE
        -TQJEEQ
         ======
          TXFUPL
         -TQJEEQ
          ======
          ??????

base: 13
letters: EFGHJLNPQRTUX
difficulty: hard
missing: H