There are essentially two modes (values are just examples):
<duration const="30 4"></duration>
<duration const="">5</duration>
In the first mode, we have two values (30 and 4). The 30 is the base duration value, the 4 is the Skill divider that is subtracted from the base duration, like this:
(30 - (SkillLevel / 4))
This means that the higher the skill divider is, the less the Skill level reduces the base duration.
Example of SkillLevel at 100:
(30 - (100 / 4)) = 5 seconds
Example of SkillLevel at 40:
(30 - (40 / 4)) = 20 seconds
Now this is the part I'm unsure about, but I believe the resulting value is also inversely modified by the Tool Quality as a percentage. Meaning that with a tool quality of 0 the duration would be doubled, and at a tool quality of 100 it would be unmodified. This could easily be tested and measured of course. It would be nice if someone could do that.
The second mode:
<duration const="">5</duration>
The duration is just a constant value, i.e. it takes 5 seconds regardless of skill level or tool quality.
For Uprooting, I recommend something like:
<duration const="14 10"></duration>
I hope that helps. Now I hope y'all can stop bugging me about ability durations!
