This post on nat1blogging (that I stumbled upon randomly) details a tricky method for trapping characters with a high perception. I'll just sum it up here (TL;DR), please read the original in case you're interested in details:
Cover a pit full of nasties with an Illusory Wall as its floor, lead the party onto it, allow them to roll perception checks to see through it, have the successful ones fall through it.
Does the above really work in 4e? Because afaik in 3.x it would not, since the Illusory Wall of 3.x does not stop physical objects from falling through it, and touch reveals its nature - so anyone walking onto it would immediately fall or be allowed a reflex save or something to back off from it. But that's not the point. What I'd like to learn is whether this would really work in 4e.
Please note that I am not familiar with 4e, obviously.