Arterial Strike (General)

Your sneak attacks target large blood vessels, leaving wounds that cause massive blood loss.

Source D&D tools

( Song and Silence: A Guidebook to Bards and Rogues, p. 38)

• Prerequisite Base attack +4, sneak attack ability,
• Benefit If you hit with a sneak attack, you may choose to forgo +1d6 points of extra sneak attack damage to deliver a wound that won’t stop bleeding. Each wound so inflicted does an additional 1 point of damage per round. Wounds from multiple arterial strikes result in cumulative blood loss–that is, two successful arterial strikes do an additional 2 points of damage per round. Blood loss, whether from one such wound or several, stops when the victim receives one successful Heal check, any cure spell, or any other form of magical healing. Creatures not subject to sneak attacks are immune to this effect.