The phrase "render inert" implies the act of making something inactive or ineffective. Therefore, its antonyms would be words that represent the opposite of this action. These antonyms may include "activate," "energize," "stimulate," "empower," or "reactivate." When one activates or empowers something, they provide it with more energy or power, making it more effective. Similarly, when something is stimulated, it becomes more alive and aware, resulting in greater productivity. Finally, to reactivate something is to revive it back to its initial state of functionality. As such, these antonyms can be useful when considering ways to enhance or improve the effectiveness of a particular substance or object.