When a great responsibility has been given to someone, they must be willing to accept it and act accordingly. In such situations, it is essential to have words that can express the weight of the task. Some synonyms for the phrase "great responsibility devolves on" include significant duty, monumental undertaking, demanding task, important burden, and crucial obligation. Each of these words emphasizes the magnitude of the responsibility and the importance of taking it seriously. It is essential to recognize that when such a responsibility is given, it must be approached with the utmost care and diligence, to ensure that it is fulfilled to the best of one's ability.