Balance on the Sky p. 75
With arms spread wide, you step onto the air.
You gain the benefits of the Air Walk spell (PH196), except with a range of personal and a duration equal to however long you remain in this stance. You must keep at least one hand empty while using this stance. Moving upward requires you to spend 10 feet of movement for each 5 feet of elevation you gain.
You gain the benefit of air walk only while you maintain this stance. If for some reason your stance ends while you are in midair, you fall to the ground as per the Air Walk spell's effect.
This stance is a supernatural ability.