Hunter's Sense p. 88
You sniff at the air like a hunting animal. After you focus your mind, an array of scents that normally eludes your awareness become clear to you.
Your mastery of the Tiger Claw discipline allows you to become attuned to the feral side of your personality. On a fundamental level, you begin to think more like a wild beast and less like a civilized creature. Your enemies are prey to be hunted down and slain. Your allies are packmates. This shift in view spreads to your physical senses.
As long as you are in this stance, you gain the scent special ability (MM 314).