Deem adverbs are provided in this article. The words listed here are commonly found along with the verb deem in sentences. This reference page helps answer the question what are some adverbs that describe or modify the verb DEEM.
fondly, hardly
highly, justly
probably, rightly
scarcely, surely
Hope this word list had the deem adverb you were looking for. In addition to adverbs used with deem, other example verb adverb pairings can be found on this site.
You can help by adding more adverbs in the comments. Thanks.