以牙还牙

an eye for an eye, a tooth for a tooth (idiom); fig. to use the enemy's methods against him

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

to use violence to curb violence

to oppose each other with equal harshness (idiom); tit for tat; measure for measure

to use an opponent's own methods to obtain retribution (idiom, from Song dynasty neo-Confucianist Zhu Xi 朱熹); to get revenge by playing sb back at his own game; to give sb a taste of his own medicine

to cure ills with poison (TCM); to fight evil with evil