If the poisoned piece is still poisoned after 5 moves, it is removed from the board. Since, in reality, a person who is poisoned is usually expected to remain bedridden for a while, I decided to freeze a poisoned piece on its square, unable to move, for the duration of its poisoning. The Doctor is designed to alleviate the poison injected by the Harpy. The Doctor moves and captures like the orthodox Queen. A poisoned Doctor must then spend a move healing itself, or let the army continue its carnage and die instead.
Pawns move as normal, with the two-step option on the first move.
En passent is possible. Therefore, I will not allow a sex change to take place in my variants. I decided, after some thought, to allow the Pawn to promote to the Rook, even though it is not present at the start of the game. Note that a Pawn cannot become a Harpy or a Doctor, as a soldier cannot simply grow a stinger and years of medical training are required to become a Doctor. A King is in check when it is attacked by an enemy piece.