At the Old Lady can be up to level 30 due to a Yang can reset the skill. This gets you back every skill point.
Skill sets you back if you want to start a new doctrine or one skill have more then 17 points. If later in the game, the skills jumps more then 17 points you can use Band of Oblivion or Skill Redistribution.
If the skill is not mastered on 17 points, you can try again.Old Lady dont guarantee that the skill will be mastered on 17 points
The price increases per level by 2000 Yang.