The Chessboard of Gwenddoleu ap Ceidio (Gwyddbwyll Gwenddoleu ap Ceidio):

[The Perilous Dreamer]

The Chessboard of Gwenddoleu ap Ceidio (Gwyddbwyll Gwenddoleu ap Ceidio): if the pieces were set, they would play by themselves. The board was of gold, and the men of silver.

[The Perilous Dreamer]

Rather large chess board with pieces of silver and crystal and the board made of gold. The pieces only play by themselves if all the pieces are set up correctly.