Radiant Sac

"“The skin at the back of your head sloughs away from your skull, forming a softly glowing pocket of gas. With probing tendrils integrating with your brain, the sac detects danger and injuries and produces a gas that grants you increased movement and focus in accordance with the threat.” —In-game description"

Effects

 * +2 Speed and +2 Crit per 5 Health Lost
 * +40 Critical Hit