Pin Advanced Puzzle (Rated 1557): Spot a Pin — Win Material

A pin becomes powerful when a valuable piece cannot move without exposing something more important behind it, especially the king. In this middlegame puzzle, White must recognize that an apparently active black piece is vulnerable to a direct tactical refutation. The key idea combines a pin with a skewer: the attacked piece is restricted, while the king behind it makes the tactical pressure decisive. This is a classic example of turning a defensive-looking position into a winning material gain.