Streetwise Utility 2City Rat
Like a rat, you are particularly skilled at using the environment, as well as your companions, to stay out of sight.
Free Action Personal
Trigger: You end a move action and have cover against at least one creature
Effect: You make a Streetwise check in place of a Stealth check to become hidden from any creature against which you have cover.
Published in Player's Handbook 3, page(s) 175.