The Cardinal and Marshal pieces are introduced on a 10x10 board.
Grand Chess is played on an enlarged 10 x 10 board with two additional pieces, the Marshal and the Cardinal.
The Queen and King sit next to the Marshal and Cardinal.
Grand Chess adds a Marshal and a Cardinal, both of which combine the power of a Knight with another either a Rook or a Bishop.
The Marshal moves as if a Rook and a Knight.
The Cardinal moves as if a Bishop and a Knight
On reaching the eighth or ninth ranks, a pawn can choose to promote or continue as a pawn. Promotion is mandatory on the tenth rank.
A Pawn can only promote to a captured piece of the same color. If none are available (no non-pawn captures have taken place thus far) then the Pawn cannot proceed on to the tenth rank.
En passant rules remains the same as Standard Chess.
Check and Checkmate rules remain the same as Standard Chess.
Stalemate conditions remain the same as Standard Chess.
Draw conditions remain the same as Standard Chess.
Winning conditions remain the same as Standard Chess.