I made this page! If you do any more damage testing or find out the direct scaling per percentage of damage resistance you have, please do share! Other than that, this is easily the strongest consumable in game in my opinion.
It gives 20% of the resistance you're missing toward 100%. at 0% it would add 20%, at negative resistances it would give even more. at 50 it would add 10, at 75, it would add 5, at 90 it would add 2 and so on.