Find the kernel of a discovered attack for Black. He has the queen-behind-bishop pattern horizontally on the sixth rank. He has a target, too; he could play QxQ for free if the bishop on b6 were out of the way. Again we have a clear view of the problem; we need something violent and distracting for the bishop to do—probably a check, but at the moment the bishop can’t threaten White’s king, which is on a light square. We need to move the king. We even can see where: if it could be forced onto g1, Black could play BxB+ and win the queen. The methodical way to pursue this is by experimenting with checks using Black’s other pieces. There is just one to consider: Rxh2+. How would White respond? He has two legal moves: Kg1, which is what we want, or KxR, which is more likely and doesn’t immediately help us. Okay; but imagine the position after KxR; look for your next check. The only piece that would have the power to check would be the queen. Qh6+ gives check while still staying on the sixth rank and preserving the kernel of the discovery. White’s only legal move this time is Kg1, and then the discovered attack BxB+ works to win White’s queen.