I understand bene to roughly mean well, good, or rightly so from Latin, while neg- coming from Latin negare to roughly mean deny, negate, or against.
The words benefit, beneficial, and benefactor all represent a person or characteristic that yields a positive result or influence. Do any of these words have an antonym that includes the neg- affix? Are there any positive bene-based words that have a neg-based word as its antonym?
Mono- and poly- seem to be frequently paired in an antonymic relationship — does this occur with bene- and neg-?
*Background: I started titling a pro and con list with benefit, and found myself searching for negefit.