Complex sentence: In Mulder's reverie he is now an old man, accompanied by an ageless Smoking Man who tells him that Fowley, Deep Throat, Samantha and Scully are now all dead.
Split into simpler sentences: In Mulder's reverie, he is now an old man, accompanied by The Smoking Man who has not aged. The Smoking Man tells Mulder that Fowley, Deep Throat, Samantha and Scully are now all dead.