When it comes to finding synonyms for the phrase "powerful ugly", there are a few options that come to mind. Some of these include words like formidable, intimidating, daunting, and menacing. These terms all evoke a sense of strength and power, but also emphasize the unattractive or unpleasant qualities of the subject at hand. Other possibilities might include words like brutish, grotesque, or unsightly, which again highlight the negative attributes of the thing being described. Ultimately, the choice of synonym will depend on the context in which it is being used, as well as the specific nuances and associations that different words may bring to mind for the reader or listener.