Definition
To use the same methods that someone else uses, especially in order to gain an advantage over them.
以其人之道，还治其人之身；利用某人惯用的手段或策略来对付该人。
He's good at spreading rumors, so we decided to play him at his own game and let him experience being hurt by rumors.
他擅长散播谣言，所以我们决定以其人之道还治其人之身，让他也体验被谣言伤害的感觉。
This company always uses unfair business practices to defeat its competitors, but now we will play them at their own game.
这家公司总是用不公平的商业手段打击竞争对手，但现在我们会用他们自己的方式来对付他们。
Politicians often attack each other in debates, so he shouldn't be surprised when his opponent plays him at his own game.
政治家们在辩论中经常互相攻击，所以当他的对手以其人之道还治其人之身时，他不应该感到惊讶。