The celestial light-shield is a great dome of luminescent energy that can be created to cover whole towns or cities. It is part-elemental, part-ethereal and is normally brought about by the placement and empowering of globestaves at various "milestone" locations about a town or city.
The command SHIELDED is available to various Avalonians by default: barons, guildmasters, the juniors, those of True Fighter status without citizenship and members of the Loremaster and Thief profession. It is available to others if there is a globestave fixed in the location since its light emanations aid perception when it comes to assessing the celestial shield (and its power-source locations).
The command makes a survey of all the focal-point locations from which the celestial dome derives its power - the milestones dotted about a town or city - and will tell you either about your home-city or the town/city on whose soil you stand when typing the SHIELDED command.
You will discern whether it is dark or "lit" in each of the focal-point milestone locations. Dark locations are unable to give power the brilliant shield of light (an enormous dome of luminescence capable of protecting an entire city from a wide range of invasive strikes and trespass - whether magical, mystical or merely belligerent). Lit locations contribute to the dome-shield potential, dark ones do not. Should ALL the milestone focal locations become lit, the magnificent dome of light will come together overhead; the city it shields will thereafter benefit from all its protections and advantages. It will remain in place until pro-actively destroyed or until one of the milestone focal-point locations is attacked so it can no longer send power into the celestial dome.
The most popular way to engender the empowerment of the great light dome is through globestaves and the "light" power - see HELP GLOBESTAVES for more information. The GLOBE EMPOWER command, once the light shield has been brought into being, can be used to maintain its integrity. Each time it is called to protect the locations beneath from violent intrusion there is a 'cost' in power - this cost can be met by the globestaves on the ground or the city's divine globe or certain advanced professional abilities. See HELP GLOBEACTIONS for info on the divine globes (as opposed to the portabl globestave) and the GLOBE EMPOWER privilege gained by citizens of each of the four cities.