Dungeons & Dragons Roleplaying Game Official Home Page - Article (Displacer Beast)
Not sure how I feel about the displacement ability. It might be more annoying than anything, especially when you roll that 19... I wonder how that would interact with the improved crit range of say a Daggermaster...
Anyways, cool monster.
I think it's a brilliant approach. Classic displacement effects have always had a chance to screw you out of a good roll. This one is specifically designed to not screw you out of a natural 20, and avoids having to make a second roll to determine success. Brilliant!