anticlimax
n.
"the addition of a particular which suddenly lowers the effect," 1701, from anti- + climax, n..
〔李〕[anti-=opposing 相对的；climax n.高潮⇒“the way opposing climax 与渐升到高潮相对的方法”→] n.abrupt descent from the important to the unimportant（从重要内容转到次要内容的）突降法