The phrase "crowning stroke" is often used to describe the final and most significant action that completes a task or goal. Synonyms for this expression can include "finishing touch," "culmination," "climactic moment," "peak performance," or simply "finale." Another way to describe this significant event is to say that this is when the "icing on the cake" is added to a situation. Other synonyms to use would be the "endgame," "apex," or "climax" of a particular undertaking. Whether it's the final push of a marathon or the last brushstroke on a masterpiece, the crowning stroke is often the most memorable aspect of any endeavor.