It seems to have merit. Also because it is a great opportunity to force yet another piece type on the player, creating many new teams. But a Ferz is probably not the best 'bonus piece'. It cannot force mate in combination with several of the other pieces. Which is not a problem for winning KPK, where you would simply pick a piece with which it can. But this is a good opportunity to also reduce drawishness in piece + Pawn vs piece end-games, where after promotion the piece on the promotion square would get traded, so that you have to make do with the bonus piece and the piece that you happened to have left.
A 'Y' (fFbW) would have more 'winning teams', but because it is so weak some of the wins are extremely lengthy. And it would still not work together with the Mortar. And I dislike that it is not fully symmetric.
Perhaps a Camel would make a better bonus piece; it has mating potential together with all other piece types. (But since it is color bound of course not with another color-bound on the same shade.) Camel + Mortar take 74 moves, though.
I also dislike that this pair promotion would only apply to the last remaining Pawn of a player. It would probably not be too distupting to allow it on any promotion if there was no free choice in what the other piece would be. So every Pawn would have the same promotion choice, either a single piece from the initial setup on the promotion square, or a pre-determined pair of two quite weak other pieces (together not worth more than what you could get as a single piece), where the only choice is which of the two you will get on the origin and which on the destination.
I would have to think about which pieces these could be. I don't want it to be possible that they would protect each other, together they should be able to force checkmate, and one of them should be able to force checkmate together with most pieces from the initial setup.
It seems to have merit. Also because it is a great opportunity to force yet another piece type on the player, creating many new teams. But a Ferz is probably not the best 'bonus piece'. It cannot force mate in combination with several of the other pieces. Which is not a problem for winning KPK, where you would simply pick a piece with which it can. But this is a good opportunity to also reduce drawishness in piece + Pawn vs piece end-games, where after promotion the piece on the promotion square would get traded, so that you have to make do with the bonus piece and the piece that you happened to have left.
A 'Y' (fFbW) would have more 'winning teams', but because it is so weak some of the wins are extremely lengthy. And it would still not work together with the Mortar. And I dislike that it is not fully symmetric.
Perhaps a Camel would make a better bonus piece; it has mating potential together with all other piece types. (But since it is color bound of course not with another color-bound on the same shade.) Camel + Mortar take 74 moves, though.
I also dislike that this pair promotion would only apply to the last remaining Pawn of a player. It would probably not be too distupting to allow it on any promotion if there was no free choice in what the other piece would be. So every Pawn would have the same promotion choice, either a single piece from the initial setup on the promotion square, or a pre-determined pair of two quite weak other pieces (together not worth more than what you could get as a single piece), where the only choice is which of the two you will get on the origin and which on the destination.
I would have to think about which pieces these could be. I don't want it to be possible that they would protect each other, together they should be able to force checkmate, and one of them should be able to force checkmate together with most pieces from the initial setup.