Excelsior

Imagine I have a skill of 60 of any given skill

I have a 120 power scroll of that skill

I use the power scroll, then I use the skill ball

Does that take me to 120?

or does a skill ball only max you out at a maximum of 100??

And also, I can use the skill ball at any time I wish correct? Even after 21 days?

Yes, a skill ball can take you to 120 if you use a powerscroll. And yes, a skill ball can be used at any time, I used mine after playing two months.