Gain Stonemason, topdeck Province (SM 5).
Play Fortress, draw Province.
Play Stonemason, trash Apprentice, gain 2 Fortresses into hand. (F 0, 2 empty piles)
Play Stonemason, trash Fortress, gain 2 Stonemasons. (SM 3)
Play Treasures, buy Stonemason, overpay by 2, gain 2 Stonemasons. (SM 0, 3 empty piles)
You win!