The phrase "leaps in to breach" is often used to describe a bold and courageous action taken to fill a gap or meet a challenge in a difficult situation. There are several synonyms that convey a similar sense of initiative and bravery. One option is "steps up to the plate," which suggests a willingness to take on responsibility and rise to the occasion. "Enters the fray" connotes a readiness to engage in a fight or conflict, while "rushes in where angels fear to tread" emphasizes the fearlessness and risk-taking involved in the action. Regardless of the specific phrase or word used, these synonyms all capture the spirit of decisive action.