The phrase "dost a number on" is often used to describe the act of causing harm, damage or trauma to someone. However, there are several words and phrases that can be used as antonyms to convey positivity or the opposite effect. One possible antonym is to "do justice," which means to treat someone fairly or to give them what they deserve. Another antonym is to "do wonders," describing the act of creating something of incredible value or effect. Lastly, one could use the phrase "do right," as a way of indicating doing the right thing or being morally sound. Using these antonyms can help in conveying an alternative and more positive meaning.