[ShadowWalker]

I was able to get this working by using the history in the field.
In the above script I count the number of items in the history.
Compare it to the value of the field.
At the end of the script I attach a tag to the pick being advanced.
That way I can tell how many times the script has already run and I can then get the right cost.
If anyone can tell me a better way to do this please do. Thankfully the game only has 5 levels in skills. So this runs quick.