About promotion from my experience with the two apothecary games which I have designed and I had the promotion rules similar (although at the time I have forgotten the exact game from where I had took the inspiration) most often the rook is the piece of choice because on rare ocasions the extra move actually worth it. HG pointed that first to me and I tend to agree. But it is much more fuzzy probably than him and me actually though about it initially. Probably here is the same thing. But for promotion extra on the side material 1 queen, 1 rook and 1 knigh would be more than enough.
About promotion from my experience with the two apothecary games which I have designed and I had the promotion rules similar (although at the time I have forgotten the exact game from where I had took the inspiration) most often the rook is the piece of choice because on rare ocasions the extra move actually worth it. HG pointed that first to me and I tend to agree. But it is much more fuzzy probably than him and me actually though about it initially. Probably here is the same thing. But for promotion extra on the side material 1 queen, 1 rook and 1 knigh would be more than enough.