Tā yòng yīgè fǎnlì jiù bódǎo le duìfāng de lùndiǎn.
He refuted the other side's argument with a single counterexample.
Tips
grammar
驳倒 is a 动结式 (verb + result) compound: 驳 ('refute') + 倒 ('topple'). The 倒 marks completion - you didn't just argue back, you knocked the argument down. Often passive: 被 + somebody + 驳倒.
