Lesson
White to move. Main line: 1. Bg5+ Kf8 2. Bxh6+
Bg5+ performs two jobs. Vacating e3 uncovers the rook’s attack on the king along the e-file, while arriving on g5 attacks the queen on h6. Black cannot save the queen because the discovered check has priority.
After ...Kf8, Bxh6+ takes the queen and even gains another tempo by checking from h6. The bishop was not merely moved out of the way; its destination was selected to create a second threat as the rook supplied the forcing move.
For every piece blocking your rook, bishop or queen, list its legal moves and ask what each one attacks. The strongest discovered attacks combine the opened line with a capture or threat by the moving piece.