王牌

wángpái
  1. (card games) trump card
  2. (fig.) ace; star player; top performer; best asset; secret weapon

CEDICT

Entry Composition

1 王 wáng
  1. king or monarch
  2. best or strongest of its type
  3. grand
  4. great
2 牌 pái (bound form) fixed pattern for lyrics or set melody in classical poetry or music (used in 詞牌 cípái and 曲牌 qǔpái)

classifiers: 塊, 個, 張