Amber Runestone

This piece of polished amber is engraved with many tiny runes. As a bonus action, you can mentally command the stone to shed bright light in a 15-foot radius and dim light for an additional 15 feet. The light is sunlight. While the light persists, you can also use a bonus action to expand or reduce its radius of bright and dim light by 5 feet each, to a maximum of 30 feet each or a minimum of 10 feet each.