As a rapper, it is essential to have an impressive flow when freestyling rhymes. Using a syntactic approach involves being mindful of how each part of speech functions and flows with the rest. Rather than just jumbling together words and syllables as many traditional rap styles tend to do, think about creating unique word order that emphasize certain points and allow for unexpected moments.
You can even construct entire sentences out of what may seem like random words; the resulting verse can make for incredibly catchy choruses or smooth transitions from one phrase to another. Syntactic approaches are already in use among experienced rappers, but imagine what could happen if it was further explored.
Maybe some of the world's greatest verses will come from exploring what it means to take creative control over the parts of speech. No longer will you be restricted by any sort of "conventional" rhyme scheme, allowing you more freedom to craft beautiful hooks and perfect intros or outros.
Aspiring lyricists should consider giving this type of syntax-focused rapping a try in order to achieve the kind of freestyle-flow excellence we've seen from renowned rap artists like Eminem or Nas.