Tide's End: The First Age

Before the dawn of civilized species, behemoths of the underworld and titans of the sky danced an everlasting duel of dominance. Streams of fire poured from the heavens as cunning Dragons made swift pickings of the lesser creatures, meanwhile shattering earthquakes tore through the planet's crust as Basilisks carved their vast subterranean highways in pursuit of their prey. The only laws were that of the cyclic tide, whose ebb and flow commanded change throughout Apteros, above and below.
One particular night, alight with chaos as typical, their only moon met with a great dark spaceform hurtling towards Apteros from beyond the stars. The collision appeared to engulf the moon effortlessly, sending celestial debris rocketing towards the atmosphere. The explosions were thunderous, and both masters of heaven and hell stopped their games to behold the horror before them. Bakunawa, the moon-eater.
The spaceform continued its decent, body aglow with chemical reaction to the air as it shrieked through the sky before crashing into the highlands, where black blankets of smoke billowed outwards, enveloping the air, blotting out stars, and threatening to choke the suns. Shards of the moon pelted the surface for months. The smoke did not cease for years. An abyssal crater scarred the surface, so large it could pull in those flying above, and so deep that even the Basilisks dared not burrow near it.
Life on Apteros was nearly decimated. The two apex species of destruction couldn't handle the sheer scale of disaster, and suffered enormous losses in the aftermath, unable to sustain their gluttonous forms. It would be thousands of years before the skies cleared and the land began to heal.