Psy Defense is one of the six raw abilities that determine how your Hero can interact with the world.
Psy Defense determines a character's ability to absorb blows and maintain an effective mind shield around him or herself. Psy Defense directly affects a character's maximum health, as well as the power of shield abilities that he or she may use.
For every point that a character's Psy Defense improves, related attacks typically heal one additional point of damage. Also, the character's Maximum Health will increase by 2, and Psy Points will increase by 1.