Finding synonyms for the phrase "necessary act" can be helpful in conveying the same meaning in a variety of ways. Some potential synonyms include "essential deed," "required action," "mandatory task," "obligatory move," and "vital undertaking." Other options might include "crucial measure," "indispensable maneuver," "requisite step," or "compulsory operation." Whatever the specific phrasing, these synonyms all highlight the importance and urgency of a particular action or decision. By using different synonyms, writers can add variety and nuance to their language while still conveying the essential meaning of the phrase "necessary act".