A little rule alternative

What can I say except -- I didn't like dice stacking, nor drawing tokens from a bag (and putting them back before drawing again). 

d20s? I have lots of them! 

So here is a way to do Koriko's dice-stacking rules with d20s. The fail/success odds aren't too far from the alternate bag+token rules, so this should be fine. (I think. Works for me, at least, but let me know if it doesn't work for you!)