The Tablet of Destiny was an artifact of Order.
After reactivating Tiamat, Klarion removed the tablet from her, having been promised he could keep it after he had awoken Tiamat for the Light. He goaded Beta Squad, who had come to stop him, with it, though he did not reveal anything about its nature. Shortly after the tablet was removed, the previously static Tiamat became active. Klarion and his ally Blockbuster prepared to leave, but Teekl ran off with the tablet. In an adjacent room, Aqualad took it from Klarion's familiar.
After Aqualad and Alpha Squad defeated Blockbuster, Klarion attacked them, but missed. The tablet was destroyed in the blast. Though he was annoyed at the loss, he did not cry over spilled milk and quickly made his getaway with Teekl.