"Daro" is a relatively uncommon word, so synonyms for it are also relatively uncommon. However, some possible similar words that could be used in place of "daro" might include "dour," meaning relentlessly stern or gloomy in manner, or "morose," meaning sullen or ill-tempered. Other options might be "gloomy," "dreary," "dismal," or "bleak." These words convey a similar sense of darkness or foreboding, although their specific meanings vary somewhat. Regardless, if you're looking for new ways to describe a situation or environment that feels heavy or oppressive, any of these synonyms might be a good place to start.