A great or heroic deed
Their masterstroke was the Concordat of 1516, which meant an immense stride in the path towards absolutism.
Then " Slade " pull the masterstroke of the night.
Provided the price is right, this could prove a masterstroke.
Like I said, bringing him on was a tactical masterstroke.
Yet the real masterstroke is to restore the chorus to its original musical function.