The Archmage's Orrery

From publisher blurb: For centuries, the Mystic Orrery has accurately predicted celestial events and their effect on magic. But its predictions are becoming increasingly erratic, and it turns out that an Archmage of a previous age removed some parts and hid them away from her successors. Now the whole Dragon Empire is at risk as the rules of magic begin to fluctuate. Powerful wards keep the Archmage himself from retrieving the needed parts — but those wards don’t account for people like you. The Archmage’s Orrery is an 8-hour organized play adventure for 3-7 8th level characters, designed to be played in four weekly 2-hour sessions. It is the 11th icon-themed adventure in the Tales of the 13th Age series.