In the final days of the world before Ulterra, there were a number of desperate gambits employed to defend the world against the encroaching Hunger of Hadar.
Ioun, in her wisdom, was able to divine the future invasion of Hadar, and inform her followers and the other gods, giving the world an opportunity to plan for the worst.
The other gods elected Bahamut to be the warrior to fight for the world. From the point on, Bahamut began stockpiling power in waiting for the monstrous world eater to arrive. After the shocking fall of Mayka'luna, the Great Hag
at the will of Hadar, Bahamut used a massive expenditure of his godly power to save the life of the defeated goddess and bring her back to the earth. In this, his ancient enemy, Tiamat, saw an opportunity.
Before the beginning of Bahamut's stockpile of power, he met with Tiamat, and they exchanged words in the Astral Plane, a neutral location, as far as gods are concerned. Despite her chaotic nature, even the dragon goddess could see that she would suffer as well, if Hadar consumed the world. She agreed to an armistice but cunning Tiamat had a plan. She would also stockpile power, and when Bahamut was done vanquishing the encroaching world-eater, she would strike, defeating the Platinum Dragon and ruling over all of dragon-kind, as was her right.
This battle was fought in the outer edges of the astral sea, at the borders where the consciousness of our world ceases to be heard, and the song of the moon is audible.
Seeing that Bahamut had used some of his power to fly to the rescue of Maykaluna, Tiamat saw what she percieved as her chance to defeat him. After claiming the power of Bahamut for herself, she could defeat Hadar easily. Unfortunately, she did not know the magnitude of the terrible power that Bahamut had stockpiled, and the Platinum Dragon was not infallible. Although he had agreed to cease his squabbling with the Chromatic Queen for the sake of the world, Bahamut lost his patience, for patience is not a Draconic value, and he struck down his ancient enemy with the terrible power he had stockpiled for years. This power had been gathered with the express purpose of destroying a godlike entity
, and it scattered the godly essence of Tiamat through the realms. Her clerics lost their power and her dragons could sense her defeat.
While the divine dragons dueled, their forces, clerics, paladins, and dragons alike also felt the beginning of the battle. For a brief few minutes, temples and lairs around the world were alight with fire, spells, teeth, claws, and the ringing blades of mortals.
After the battle, Bahamut established The Platinum Law
, and realized that he no longer had the strength he would need to defeat Hadar. In a desperate effort, Bahamut devised a plan. The other gods, who were still at full strength, charged Hadar and engaged him at the outer edge of the Astral Sea. While they were formidable, they were no match for their chosen champion, Bahamut, and Hadar began to consume their power, one by one. While the world eater was distracted, Bahamut used The Inscriber of God
to prepare The Curse of Mirrors
, using the nearby moon as the mirror. Then, using what was left of his power to fuel the spell, Bahamut sealed the world eater into the moon. Unfortunately, the moon made for such a large mirror, that it sealed all of the gods who were fighting the terrible creature as well. The effort of maintaining the spell paralyzed the dragon god, leaving him unable to do more then send fleeting whispers to those who were faithful to him, explaining what had been done.