The phrase "mysterious ability" refers to a power or skill that is not fully understood and cannot be easily explained. It suggests something beyond human understanding, which may seem supernatural or otherworldly in nature. The word "mysterious" means unclear, unknown, or difficult to understand, while the term "ability" refers to an individual's capacity for performing a certain task or action. Therefore, when combined, this phrase implies that there is something unique and unexplained about someone's ability to perform a particular feat or possess a certain talent.