Storm Diver's Additions Mod/Celestial Barrier

The Celestial Barrier is a hardmode accessory crafted from all 4 lunar fragments. Taking at least 60 / damage grants the  Buff that regenerates 15 health per second and grants 50 defense, with the length of time being determined by how much damage the player takes. It also provides immunity to the Distorted, Obstructed, Electrified, Marked for Target, and Nebula Blazed debuffs. It also provides immunity to knockback.

Trivia

 * This accessory can be obtained after just 3 pillars have been defeated due to the fact the 4th fragment can be crafted from the other 3.