tour de force 
/ˌtuɚdəˈfoɚs/ noun
/ˌtuɚdəˈfoɚs/ noun [singular] : a very skillful and successful effort or performance
▪ The book/film is a tour de force. ▪ Her performance in the play was a real tour de force.
▪ The book/film is a tour de force. ▪ Her performance in the play was a real tour de force.
