Mason Attack

The Mason Attack arises after 1. d4 d5 2. f4. Instead of challenging the center with c4 or developing a piece, White adds the f-pawn's control of e5 to that of the d-pawn, aiming for a dark-square bind reminiscent of the Stonewall. The cost is permanent. With White's d- and f-pawns advanced, e4 becomes a hole, and the kingside and light squares are loosened. Engines give Black a slight edge, although on Lichess White still scores slightly better than Black.

The most frequent replies are 2...Nc6, 2...Nf6 and 2...e6. After 2...Nc6, which contests e5 directly, the main line 3. Nf3 Nf6 4. e3 gives White solid central control and a grip on e5. 2...Nf6 does not fight for e5 but trains a piece on e4. The engine's preferred move is 2...Bf5, which develops the light-squared bishop toward the weakened squares and is considered the most accurate reply. The mirror reply 2...f5 leads to the Bird Opening: Double Duck Formation.