A drop of unicorn blood would probably have some amazing effects!
But alas:
In the beginning section of the tutorial videos the Dark Magic used is setup with a tightened gap and thick lube on the bearing keeping it very responsive.
In the advanced trick videos the Dark Magic is setup using a KonKave bearing with a wider gap to make it completely unresponsive.
I am currently using a Center Trac bearing with no shims in my Dark Magic.