助纣为虐

1. • lit. helping tyrant Zhou 商纣王 shāngzhòuwáng in his oppression (idiom)
2. • fig. to take the side of the evildoer
3. • giving succor to the enemy

Character by character

• 助(zhù)help
• 纣(zhòu)Zhou, pejorative name given posthumously to the last king of the Shang dynasty, King Zhou of Shang 商纣王 shāngzhòuwáng
• 为(wéi)as (in the capacity of)
• 虐(nüè)brutal