Phos Astos was the last standing city of Sadre before it was raided by The Many. It is where Xanthe was born. The ''Many'' are people of Sadre who have been infected by the Wyrm. Phos Astos is surrounded by a flat, smooth black plain.
Phos Astos means ''City of Light'', it commonly has spiders as live stock and uses fungi for light and large mushrooms for homes. They have a cavern that lets in warm air and heats the city. They also have many tunnel ways and a security system (called the Screamers) that are mushroom like bells. They use the security system (screamers) to tell when the Many are coming. They have built a dam to sweep away the Many in great numbers.