In ancient times wizards tied a wild fire spirit to this stone. Normally it glows with a pale light and gives off a mild warmth (enough to keep someone warm on an icy winters day). He who bonds with the stone can awaken the fire spirit and command it to perform more dramatic actions.
The Sun Stone was carried by Edira in SY01. The Promised Land as part of her quest to take it to Thistle Hold. It was stolen by Keler but soon retrieved by the party.