Dacha Tactics #20 - Capablanca finds dark amidst the light!

An interesting endgame taken from a Capablanca game vs Janowski. Lots of funky pawns everywhere, which are strong which are weak and how to play? Well let's begin with colors! The imbalance is our Golden light bishop vs his knight which means we are +500 light and -500 dark. Our light grip is clearly formidable. The b4 pawn looks oh so juicy but alas, it is on dark which is white's color. How to parlay our light advantage to help us on dark? Leverage dacha...

Interact with the puzzle below. If you get stuck, you can always click the "lightbulb" icon in the lower-left of the puzzle frame. Good luck!