When it comes to synonyms for the phrase "hast down pat," there are many phrases that convey the same message. Some possible alternatives could be "mastered," "perfected," "nailed," "flawless," "seamless," "polished," or "expert." These phrases all suggest that a particular skill or task has been honed to the point of near-perfection. Whether it's a musical instrument, a sport, or a job task, using any of these synonyms in place of "hast down pat" will communicate the idea that someone has put in the time and effort to become truly proficient at something.