The phrase "am case" doesn't have any direct antonyms, as it is not a commonly recognized term or phrase in English. However, the individual words "am" and "case" do have a range of antonyms, depending on their context and usage. For example, "am" as a form of the verb "to be" has the antonym "am not" or "is not" in the negative, and a range of other verbs such as "do," "can," and "will" in different tenses. Meanwhile, "case" as a noun has antonyms such as "open case," "innocent verdict," or "civil suit" depending on the legal context.