The phrase "nature beast" doesn't necessarily have a clear antonym since it's not a commonly used phrase. If we break down the two words, "nature" refers to all living organisms and the physical world around us, while "beast" typically refers to an animal that's wild or fierce. Therefore, some antonyms for "beast" could be "tame," "docile," or "domesticated." On the other hand, antonyms for "nature" might include "unnatural," "artificial," or "manufactured." However, it's important to note that without proper context, it could be challenging to identify the most accurate antonyms for "nature beast.