Sneaking Guide

Official Ruling

Once a creature with power 2 or less has been blocked, Sneaking Guide’s ability won’t cause it to become unblocked.

Official Ruling

If the target creature’s power is greater than 2 as Sneaking Guide’s ability tries to resolve, the ability doesn’t resolve. However, if instead the creature’s power is raised above 2 after the ability resolves, it still can’t be blocked that turn.