The unification ceremony is an event that takes place at the end of World of Xeen. It causes the two sides of Xeen to meld together, turning the flat world into a planet.
After the defeat of Sheltem and Lord Xeen, when the Cube of Power and the Sceptre of Temporal Distortion had been retrieved, the dragon pharaoh announced that "the destiny of Xeen is in sight". If the Defenders of Xeen could complete a few more quests for him, he would be able to perform the ceremony.
He needed them to activate the machines at the corners of the Cloudside of Xeen, awaken the Elemental Sleepers on the Darkside of Xeen, rescue Prince Roland from the dungeons of Castle Alamar, and open the way to the cloud world above Darkstone Tower.
Once all the quests were completed, the citizens of Xeen gathered to watch the ceremony. Roland presented the Sceptre of Temporal Distortion, while Kalindra held the Cube of Power. Both objects were placed on the Altar of Joining, and the unification process began. A short while later, the two sides of Xeen were united to a single planet.