Twist the Skein

You tweak a strand of a creature’s fate as it attempts an attack roll, saving throw, or skill check. When a creature you can see in range makes an attack or saving throw, but before you see the result of the roll, roll a d20 and subtract 10 to produce a number from 10 to –9. Add that number to the creature’s roll. This adjustment can turn a failure into a success or vice versa, or it might not change the outcome at all.

This adjustment can change a critical hit or a critical fail to a non-critical, but it cannot produce a critical as those depend on a natural roll of 20 or 1.