Shield Pill

is a Pill that increases Barrier Power. It is useful for surviving Tribulations. It increases the Barrier Power (Value) by 30%. 
However, since all Barrier Power Bonus (Value) additions from Items (Darkarmor Talisman, Giant Turtle's Shell, Flood Dragon Scale, Secret Codex of Taiyi) are flat additions, the bonus from Shield Pill only applies to the Barrier Power Bonus from the Protect Skill, and is therefore more limited than it initially appears.
The Initial Value of Barrier Power Bonus (Value) is 0.1 at Protect Skill Level 0, and 0.175 at Protect Skill Level 20. Therefore, Shield Pill only adds 0.03 at Skill Level 0, and 0.0525 at Skill Level 20, which is slightly more than a third of the effect gained from equipping a Giant Turtle's Shell or Flood Dragon Scale.