â–ª Swan song: The last performance or piece of work that a musician, author, composer, artist, etc gives, writes, paints, etc before their death or retirement.
Derived from the legend that a swan is mute until moments before death during which it sings a beautiful song, a swan song is an action ending something epic.
Ex) After the concert, they said they would never perform together again. That concert was their swan song.
Ex) It was the team's swan song to end their season by winning the championship.