Here's another installation of the Piece-drop Mate series!
I'll try to be more explicit about the rules of the puzzle, as recommended by @Rewan Demontay.
This time, the position is one where Black wins. He makes a regular move and places a piece on the board at the same time, resulting in a position in which White is checkmated. White never gets the chance to make a move in this puzzle.
As usual, everything about the position must be legal (except for the fact that you are making a move and placing a piece at the same time, of course) (i.e. the position can't have more than 8 pawns at any given moment.)
@Rewan Demontay was such a stickler about the legality of this that I have to include the fact that position can only arise from a Chess960 position due to the bishop on e8.