So, cranking up the random number picker . . . and Comment #14 was the winner!
Pit trap reverses gravity for the first PC to fall in. 1d6 damage at the bottom of the pit plus 2d6 when you hit the ceiling. Spend next 1D6 turns walking on ceiling, knocking allies helmets off with your spear, rappelling down the up staircase, and so forth.
fadedearth, hit me up with your email address at mwschmeer AT gmail DOT com so I can get this paperback in the mail to you! You have until Friday, June 28th, to claim your prize; otherwise, I'll have to pick another winner.
Thanks for playing, folks. I'll compile all the entries into a single post & file for download soon.