Mayet's mate
A rook-and-bishop mate on the back rank: the rook checks right beside the king and a bishop keeps it safe from a distance. Also known as the h-file mate.
How it works (spoiler)
The rook lands on the back rank right next to the king, defended from afar by a bishop the king cannot reach, while the king’s own pawns block every escape. When the rook arrives down the open h-file against a castled king, it’s also called the h-file mate.