The Tablets of Fate were stone slabs on which the official portfolios of every one of the deities of Abeir-Toril were written. Bane and Myrkul stole the tablets from Ao and hid them in Faerûn, suspecting that some of the Overgod's power was derived from these tablets. When Ao discovered the Tablets of Fate were missing he summoned all the deities and asked for those guilty to hand them over. When no one stood forward to admit to stealing the Tablets, Ao cast down all the gods from the heavens, taking their divine power in the process. Ao tasked Lord Helm with guarding the Celestial Stairways which would lead the deities back into their divine realms. For this he retained his divine powers. Before the Avatar Crisis ended, Bane and Myrkul were both slain, although Bane would return in 1372 DR.
The suspicions of Bane and Myrkul that some of Ao's power lies in the tablets seems confirmed, as Ao appeared unable to recover the tablets himself. Ao suggests that the tablets had little power, serving only as reminders to the gods of their duties.
However Ao himself destroyed the tablets, grinding them into powder.
The tablets are described as plain clay tablets, less than two-feet high, with the name and portfolio of every deity inscribed in glowing blue-white runes.