There are many synonyms for the phrase "doeth something it" that can be used to add variety to one's writing. Some common synonyms include "performs," "executes," "accomplishes," "fulfills," "completes," "carries out," and "undertakes." Each of these words carries a slightly different connotation or emphasis, so it's important to select the right synonym based on the tone and context of the sentence. For example, "performs" implies a level of skill or expertise, while "carries out" suggests a sense of duty or obligation. By using different synonyms, writers can make their writing more engaging and dynamic for their readers.