Thanks Shadow. They should both say this round.
Here is an excerpt from our upcoming FAQ, which may help with understanding the difference between an attack, and an attack action.
An attack action is a creature action (quick or full) used to make an attack. Sometimes the attack action will be an individual attack, or it might comprise multiple separate attacks. For example, double strike, triplestrike, and sweeping are one attack action, but consist of multiple individual attacks. A zone attack is a single attack action with a separate individual attack made against each object inside that zone.
So, the Piercing applies to the very next attack, not a full attack action of multiple attacks.
If all goes well, this FAQ will be available by Monday. Shadow, do you have time tomorrow to proofread sir?