万弩俱发wàn nǔ jù fā

ten thousand crossbows being discharged together; all bows shooting at once
❍ 庞涓果夜至斫木下，见白书，乃钻火烛之。读其书未毕，齐军～。魏军大乱相失。(《史记·孙子吴起列传》)And sure enough; when Pang Juan came to the tree in the dark and glimpsed some writing on the bare trunk,he struck a light. Before he could finish reading,ten thousand crossbows were discharged together and the army of Wei was thrown into confusion.