Earthfall

After millennia of fighting, the gods from all sides eventually agreed to lock themselves behind the divine gate except for @Rovagug the devourer. The other gods attempted to restrain him and drag him behind the gate, during the conflict Rovagug cut off the left hand of Abadar, but the combined might of the gods proved too much and the creature was restrained. In a last ditch bout of spite, called forth an unborn planet to crash and destroy the world if he would be denied the right to consume it. The planet hurled towards the world and in an effort to shield the world, Acavna goddess of the moon sacrificed herself by allowing the moon that was her domain to intercept the planet before it destroyed the world. The plan was successful in that it shattered the fetal planet but the fragments still fell unto the planet. The smaller impacts while they weren't enough to destroy the planet, plunged the world into darkness for 100 years and brought an end to the great god civilizations of the past.
The earthfall also had other unforeseen effect such as the long lived races only living 80 years before a sudden death with no external causes took them. Magic seemingly degraded and by the time the sun emerged much of the landscape had changed, Rovagug may have failed to destroy the world, but some would argue it managed to destroy civilization.