Darkened adverbs are provided in this article. The words listed here are commonly found along with the verb darkened in sentences. This reference page helps answer the question what are some adverbs that describe or modify the verb DARKENED.
carefully, completely
considerably, gradually
partially, slightly
slowly, suddenly
utterly
Hope this word list had the darkened adverb you were looking for. In addition to adverbs used with darkened, other example verb adverb pairings can be found on this site.
You can help by adding more adverbs in the comments. Thanks.