Find the kernel of a discovery for Black. His queen is masked by the knight on c6; his bishop, as in the previous case, is masked by the knight on f6. So now think about the targets available for the masked pieces. The knight on c3 is protected by a pawn, making it an unappetizing target for Black’s queen. But the knight on d4 is another matter. It is protected once, but by White’s queen; and it is attacked once already by Black’s knight on c6. This suggests two sorts of possibilities: play the discovery with Ng4+ (the same idea seen in the previous problem); then after the knight gets taken, play BxN. But of course this move order gains nothing. It’s just a trade of pieces. So consider the other move order: play the exchange NxN first; if White replies QxN, play the discovery Ng4+, winning the queen. Again, a preliminary exchange serves to upgrade the target.