Odic Shields and Shrouds of Concealment
In magical theory and practice, [an odic shield is] a field of etheric energy established around the outer edge of the human aura to protect the user from hostile magic or assaults of spirits. Several different methods have been used to establish and maintain an odic shield. The shroud of concealment, which is used in rituals of invisibility, is a closely related phenomenon….
In Golden Dawn magic, [the Shroud of Concealment is] a shell of etheric substance built up around the magician by intensive ritual work that prevents other people from perceiving the magician. The creation of the Shroud of Concealment is fundamental to the Golden Dawn method of magical invisibility….