The Datasphere is a CUBE given to Red Mage by Thief, who received it as a passage payment from Warmech to ride on their airship. It stores information in a 612-dimensional matrix, which is enough data to encircle the universe 3.5 times. Reading a mere fraction of it could supposedly drive a man insane. Red Mage theorizes that if an insane man read it, they'd be either turned sane or killed. Wanting to test this theory, they call for Black Mage and have him read it. Black Mage subsequently goes catatonic, and the two decide to "try it on Fighter next". However, when Fighter looks into it, it has no effect on him. Fighter then informs everyone that the datasphere contains "every possible way to build every possible device to destroy every possible thing in all creation". Red Mage later cures Black Mage by telling him he has a magazine "filled with huge knockers", and gave him a magazine with door knockers in it.
In an attempt to cure himself of his "monsterism", Red Mage looked into the datasphere. It drove him insane, and apparently emptied the datasphere of its information. When the dark god asks Black Mage if he'd absorbed the datasphere's information, Black Mage says he did look into the sphere and could "see the way the gods do". However, he then got distracted and forgot the information, frustrating the dark god.
After recovering from the massive intake of the datasphere, Red Mage claimed to know "All of the moves in the game", and has hinted on knowing a way to destroy all existence, including Sarda. However, Red Mage admits, after Sarda absorbs the powers of the Orbs and the Fiends, that the Datasphere says nothing about how to destroy "anything that could not exist," which included a more powerful Sarda.