Queen mates with a defender forming a triangle with the king
A queen delivers mate from a square diagonally next to the king, defended by another piece so the king cannot capture. The queen, defender, and king form a triangle. The king's other escape squares are covered by the queen itself or its supporters. Often built around a knight or rook defending the queen one knight-move away.
Queen to g4. Mate. The queen checks the king from g4. The white king cannot move: h4 is covered by the queen, h2 by the rook on g2, and the queen on g4 is defended by the same rook so the king cannot capture.
3 more clean runs (at any point) to reach Recall.
Black to move. White king has slipped to h3 thinking it has shelter behind the pawns. Black has a queen on e4 and a rook on g2.
3 more clean runs (at any point) to reach Recall.