He has spotted the weak d6-square.

This octopus rules! Black’s rooks are at a loss.

20…b6? is refuted by 21.♕f3.

And White won material and later the game: …1-0 (50).

White increases his space advantage, which results from his central passed pawn, and intends to drive the black pieces further back.

15…♗c6 16.f3 a6 17.b4 cxb4 18.axb4 ♕d8

18…♕xb4 19.♖fb1 is a trivial queen catch.

Solid support of the central striker now.

Opening up the b-file and the queenside for the rooks. The end is near.