Can you increase the DC and healing of Treat Wounds with Natural Medicine?

Question

I noticed a strange skill interaction while trying to make a build for a Primal witch. The Treat Wounds skill action specifies that the DC and amount healed by the skill check can be increased based on your proficiency with Medicine:

"If you’re an expert in Medicine, you can instead attempt a DC 20 check to increase the Hit Points regained by 10; if you’re a master of Medicine, you can instead attempt a DC 30 check to increase the Hit Points regained by 30; and if you’re legendary, you can instead attempt a DC 40 check to increase the Hit Points regained by 50. The damage dealt on a critical failure remains the same."

However, the Natural Medicine skill feat lets you "use Nature instead of Medicine to Treat Wounds." The use case of this is clear for a basic Treat Wounds action, but less clear for the alternative DCs. Would you replace all instances of "Medicine" with "Nature" for the purposes of attempting a higher DC, or would the character need to also have the requisite proficiency in Medicine in order to raise the Treat Wounds DC?

Answer 1

You can increase the DC based on Nature proficiency

Alright, the rules are mostly silent on this, but there is good evidence that you should perform Treat Wounds in a way that is essentially replacing the word "Medicine" with "Nature".

1. Foremost, it makes sense. The feat would be nearly useless* beyond around level 5 if you had to increase Medicine (also a Wisdom skill, with more availability of Item bonuses) to keep using your Nature bonus.
2. The phrasing on similar but different abilities shows is more ambiguous, suggesting that at least Natural Medicine should work in the way you describe.

• Acrobatic Performer "You can roll an Acrobatics check instead of a Performance check when using the Perform action."
• Graceful Leaper "You can roll an Acrobatics check instead of an Athletics check when making a High Jump or Long Jump."
  • "roll a check" is slightly different than "use Nature", sounding more like a single die replacement than a shift in the Activity's function

The writing could just be different authors, but I think the intent is pretty clear; the new skill can be used like the skill it's replacing. I think this is true of all of these abilities, but Natural Medicine is the most clear that it should completely replace its original skill for the given Activiity.

*Natural Medicine is already of dubious utility given the importance of other Medicine Feats (which it does not allow you to qualify for) to the Treat Wounds activity, unless you are taking Herbalist Dedication.