You have mastered the double nock to the point that you can (almost accurately) nock and fire three arrows at once.
Benefit: As a move-equivalent action you can nock three arrows to your bow instead of one. In this way, your next attack with your bow will fire all three arrows at your target. You make an attack roll with each of these arrows, with each attack suffering from a -5 circumstance penalty on the attack roll.
Undefeatable: The Collected Feats Sourcebook, Copyright 2009 – 2010, Louis Porter Jr. Design, Inc. Undefeated, Copyright 2011, Louis Porter Jr. Design, Inc.