助桀为虐 (zhù jié wéi nüè) | Meaning: (idiom) to help Jie, the tyrant, in his cruel deeds; fig. to aid an evil person in doing evil | Chinese Idiom with Pinyin & Origin

(idiom) to act as accomplice to a villain; to assist in wrongdoing为虎作伥wèi hǔ zuò chāng

lit. helping tyrant Zhou in his oppression (idiom) · fig. to take the side of the evildoer · giving succor to the enemy助纣为虐zhù Zhòu wéi nu:è

accomplice · accessory帮凶bāng xiōng

(idiom) to help Jie, the tyrant, in his cruel deeds; fig. to aid an evil person in doing evil