How'd that get there

You are able to hide your stab confusing your attacker. As a primary action and move action using a Piercing weapon, your attack strikes as though it is a telling blow. Once you have attempted this on an opponent once, or others have seen you use the trick, the attack is no longer a telling blow. You must be wearing a robe or cloak, have some way of concealing your weapon or striking from being hidden to use this Prowess. At 8th level, even a scarf or ribbon is sufficient. At 15th level no concealment is required, your weapon is the magic trick.