The phrase "mysterious power" refers to a force or ability that is difficult to understand, explain or predict. It suggests something that has an air of mystery around it and is often associated with the supernatural or unexplained phenomena. This expression can be used in various contexts such as describing someone's charisma, a hidden strength or talent, or even a mysterious force of nature. Ultimately, "mysterious power" conveys an impression of something that is beyond our normal understanding and cannot easily be explained through conventional means.