Where does White have the makings of a discovered attack? On the c-file. But once more only the queen-behind-bishop kernel is there; the queen lacks a good target, and the bishop has no checks to give, although it can attack Black’s queen with Bxe6. So again think about what it would take to make the tactic work. (a) First, the pawn on c7 would need to be replaced by a better target. So consider taking the bad target with one of your other pieces (like the White knight on b5), and ask whether your opponent would have to recapture with a more valuable piece. (b) Second, it would help to have a better target for the unmasking bishop to threaten—preferably Black’s king, which unlike its queen would not be able to move and cause trouble when attacked. Black’s king is behind its queen, but the queen protects the same pawn on c7 that we are trying to trade for a better target. The solution to the problems at both ends becomes obvious: White plays Nxc7; if Black recaptures QxN, White has a check for his bishop with Bxe6 and a target for his queen in the loose Black queen on c7. The lesson repeats: be clear about what obstacles prevent your idea from working; often two problems can be solved with a single stroke.