The word "mystifies" means to cause confusion or bewilderment, and there are several synonyms that can be used in its place. One such synonym is "puzzles," which implies a challenging or difficult situation that requires careful consideration to solve. Another synonym is "baffles," which suggests that something is surprising or hard to understand. "Confounds" is also a good synonym for mystifies, as it implies a sense of being dumbfounded or left speechless. Finally, "perplexes" is another synonym for mystifies, communicating a sense of confusion and uncertainty. Whatever word is used, the idea is to convey a sense of confusion and bewilderment.