Complex sentence: Dave Freer is another regular science fiction writer in Baen's stable of writers and contributed which introduces three characters that play a role in the as one of several prequels in to Flint's Novelette "The Wallenstein Gambit".
Split into simpler sentences: Dave Freer is another regular science fiction writer in Baen's stable of writers. He contributed which introduced three characters that play a role in the as one of several prequels in to Flint's Novelette "The Wallenstein Gambit".