[Autumn]

You can still gain stacks of Sturm when you have 0 levels in the skill, via Asura fist and proccing Geist Schritt, when you proc sturm levels in this method the meter for it will never go down, despite capping at 4 you can see how this is a problem.

To replicate:

Put 0 levels into Schwarz Sturm
Use Asura fist and hit a target or Proc Geist Schritt against any applicable situation.
Move or do any skill that isn't related to boxer and your sturm levels will never decrease.