A shield pack is a backpack with a limited carrying capacity due to the phlogiston bioler and mechanisms concealed in its interior. These mechanisms connect to large mechanical arm that reaches around the wearer and ends in a heavy wooden shield. When devices concealed behind the shield detect an incoming attack, the shield swings to block it. However, as the movement of the shield is automatic, it often gets in the way of the wearer's attacks as it protects her. When turned off, the shield arm folds away over the back of the pack.