It may take too many coins and perhaps goes somewhere else.
The essential points would be:
In a massive fight between good and evil in the outer planes, a powerful and titanic magical item was cast into the astral plane because it had been severed from it's main piece but not before sucking the main combatants in as a prison. As it floated in the astral plane, the inherent magic that was bleeding off energy, like a red hot nickel ball cooled a crust onto the surface, grew small bacteria called "creatures", and was readily able to be mined for magical materials such as residuum and quintessence. It is literally bleeding off uncontained magical fonts. The gods are emanations of belief but not of the creatures, of the item's residual memory of the energy it fed off of during the war. It makes manifestations of deities that infect the minds of the creatures to help bleed off the residual energies of the core.
Now . . . whether the creation of gods by the item and the belief in them by the creatures creates manifestations of them in the outer planes would be an interesting idea to look into and what sorts of chaos that would cause for those who fought the war.
This is just one example of how that could have happened:
There was an item made in the forges of Mechanus that was stolen by a fallen angel (Name____) being chased by a repentant demon (The Flagellant?). It was a Godseed. Used in accordance with the laws of order, it would be used to make a new world on a material plane. It was sought by many.
It caused a great war that raged through the planes. By the time the demon caught up with the angel, armies had been formed on both sides. To increase the seed's vitality, it had been brought to Limbo and was being loosely protected by unaffiliated hordes of slaads that surrounded the abandoned Gith Fortress. Along the way the seed had been poisoned by ______ but blessed by ______. It was planted in Limbo and it began to sprout but somehow the seed was severed from the stalk. The Flagellant knew the Fallen One would not stop and so wrestled it into the split seed as it was cast into the ether. Their struggle and fight within the core of the seed is what churned the magical energies enough to make a world. Simple manifestations of the idea of them on the surface represent the ongoing battle within the very fabric of the plane.
Some agents know this and actively seek to weaken the scars of the world enough to release the prisoners back to the outer planes. Some seek to protect it.
This is just an idea.