以眼还眼，以牙还牙

yǐ yǎn huán yǎn , yǐ yá huán yáyiyanhuanyan,yiyahuanya

1. an eye for an eye, a tooth for a tooth (idiom)
2. fig. to use the enemy's methods against him
3. to give sb a taste of his own medicine

Study it in Yanamino