The phrase "more hundred-to-one" typically implies a situation where the odds are greatly against something happening. So, the antonyms would be words or phrases that suggest the opposite; that is, where the chances of something happening are high or even certain. Some possible antonyms could be phrases like "likely," "probable," "even odds," "balanced chance," or words like "certain," "definite," "sure thing," or "assured." Essentially, any term that conveys the idea of a positive outcome or a higher probability would be an antonym to "more hundred-to-one.