Skewer Advanced Puzzle (Rated 944): Skewer — Win the Rook

In this chess endgame, an open file becomes the highway for a decisive skewer. Black's rook transfers to the file where the white king and the white rook are both standing, forcing the king to move and exposing the rook behind it. An equal-looking rook endgame collapses once the defender's king is caught in the open. With the white king centralized but exposed, every check carries extra venom. One precise move turns the position into a decisive material gain, leaving Black a clearly winning rook endgame.