The word "be muse" means to inspire or fascinate someone. Its antonyms would be words that convey the opposite meaning, such as bore or discourage. These opposing words would be something that does not spark creativity or wonder. Alternatively, to be banal or uninteresting would also work as antonyms of "be muse." These words are essentially the opposite of what one would want to convey if they were trying to inspire someone or get their creative juices flowing. While there may not be many direct antonyms for "be muse," there are certainly words that could be used to describe the opposite effect.