他在棋局中用一个巧妙的计谋骗过了对手。

He used a clever ___stratagem to deceive his opponent in the chess game.

他在扑克比赛中使用了一个巧妙的策略，让对手误以为他有一手好牌。

His clever ___stratagem in the poker game made opponents think he had a strong hand.