I'm unclear about what happens when Muck Graul is undefeated. Here's the text verbatim.
--------------------------------
If undefeated, another random character at this location encounters Muck; put Muck on the bottom of this location deck
--------------------------------
I think this means that if the character that first encounters Muck fails, It fights someone else. If that fails, it fights someone else again. This continues until either someone finally beats it, or Muck has fought everyone there. In which case, it scampers to the bottom of the location deck.
That's what I think it means, but they way the text is printed, it's really unclear. Does it magically clone itself with one fighting some other random random while the other goes to the bottom of the location deck? If the second character is unable to beat it, is the original character eligible for another encounter with Muck? This text has too many unanswered questions.