Garthanos
Arcadian Knight
Yeah, well, how I would do it is you have your basic effect, which is that knowing this practice provides narrative justification for making a Nature check to achieve a success in an SC when obscuring your tracks would be a narratively appropriate means to achieve a success (or some other type of SC-related check, say if you called it a 'secondary skill use' to gain an advantage or whatever). If you're willing to pay the specified price, say one HS, then success is automatic.
So, rituals/practices provide 2 advantages to those who master them. They provide the player with plot power, she can justify doing things and using skills that might not otherwise be possible.
like enabling you and allies to use charisma based skills to discover information that normally would require perception because you speak with the dead.
Secondly they allow an automatic success in return for paying a price.
A normal use of nature might allow track obscurement but would slow the rate of your travelling while you did the obscurement. A healing surge might remove the slowing and make the roll automatic. However with just that model it still leaves the situation where it can easily be just wasted effort only used extremely rarely when you know you are being tracked. (hence my not quite congealed thoughts on hunters empathy to bring a sense of certainty to it) ... hunters empathy would also cover that tingling on the back of your neck when you are followed that rogues like so much.