Guardian shields can be deployed by sentries to protect friendly units and reduce damage from ranged attacks. They are created by weaving light into a semi-solid state. Through this, the sentry can surround itself with an area-encompassing shield to safeguard protoss ground forces. Projectiles or energy blasts that penetrate the field lose some of their kinetic or thermal energy, and part of their effectiveness. Due to its considerable coverage radius, the guardian shield is not powerful enough to make much of a difference against larger types of ordnance.
Sentries can create a radius 4.5 aura which reduces incoming ranged damage to friendly units by 2.