More simple stuff. A battery can work in a similar way when the mating square has protection from above rather than from the side. Here White again has two pieces trained on e8, and Black’s king is stuck behind its pawns. The e8 square is protected once, by the knight on f6; a piece that sits on the mating square, like Black’s rook here, is not contributing at all to its defense. So it’s two against one, and again White wins. 1. QxR+, NxQ; 2. RxN#.