"With telling effect" is a commonly used phrase to describe something that has a significant or powerful impact. There are various synonyms that can be used to replace this phrase, including "strikingly effective," "potently impactful," "powerfully eloquent," "compellingly convincing," or simply "effective." Each of these synonyms can be used depending on the context and the tone of the statement. For example, "strikingly effective" might be more appropriate to describe an advertising campaign, while "powerfully eloquent" might be used to describe a speech. Choosing the right synonym can help to convey the message and the intended impact more precisely.