变戏法 literally means 'to perform magic tricks' (戏法 refers to traditional Chinese magic, distinct from Western 魔术). It's a separable verb (离合词): the verb 变 can separate from the object 戏法, letting you insert measure words or modifiers between them — 变了一个戏法 ('performed a magic trick'). It's also used figuratively to describe deceptive behavior or clever tricks, like juggling facts or pulling a fast one on someone.