The phrase "am needful" can be replaced with various synonyms depending on the context. For instance, phrases such as "I require," "I necessitate," "I need," or "I demand" can substitute for "am needful" when talking about one's needs. In the case of expressing one's priority, one could use "I am essential," "I am crucial," "I am important," or "I am indispensable." Conversely, when talking about someone else's or something's importance or necessity, "it is vital," "it is required," or "it is essential" can be used. Overall, depending on the sentence structure and context, there are numerous synonyms for the phrase "am needful" that can be used to add variety to one's language.