turn·about 
/ˈtɚnəˌbaʊt/ noun
plural turn·abouts /ˈtɚnəˌbaʊt/ noun [count] : turnaround 2 — usually singular — often + in ▪ There was a sharp turnabout in oil prices. ▪ a turnabout in the country's foreign policy
turnabout is fair play
US — used to say that if someone does something to harm you it is fair for you to do something to harm that person ▪ She did it to me, so I'm going to do it to her. Turnabout is fair play.
