In a world of many worlds, there sits a small valley, just on the edge of livable for the humans who reside there. The call it the Great Stone Ring Lifegiving Basin, and they farm rice and yams in the rich earth at its center, and they gather the wool of the rock sheep, which the Emperor buys for the clothing of His armies, and under His protection they are only rarely attacked by rising demon lords.
Rarely, of course, is not never.
This day, to Great Stone Ring Lifegiving Basin, comes Kortizar Rakvitikos, demon lord of Life, blessed with the power to call and command the great beast and monsters of the world. He has not yet claimed many worlds, but he is mighty, one who can fight ten thousand men and emerge victorious. He has caught the scent of the Emperor's kin, and seeks to add to his lands and to claim a ransom or resource that gives him leverage against the Emperor.
The villagers have fled to the sheep tunnels, for though the army patrol is not due for weeks, it could take weeks for the demon lord's own forces to search the cliffs and passages. There they wait, and hope the shepherds don't die trying to save the fields. They can't afford to lose the fields, but without the shepherds there won't be anyone strong enough to shoo the sheep when they burrow into a house.
But Kortizar Rakvitikos has had a clever idea. When the mice hide in their burrow, you smoke them out! And so he has called together all of his strength, to summon the greatest of monsters to flood the lands with their breath. Even given his power, this is a complex ritual, requiring all the skill his master had imparted to him, as well as the deep wisdom and strength of the Tree. Thankfully this pitiful village is less impoverished than he had thought, with a strong connection to the Tree that even includes the element of Life. Had they been a mana-bereft backwater, he might not have been able to crush them so utterly!
It is an impressive working. While they shall not remain bound for as long as his loyal demons, each will be a great force, mightier than he himself, with true mastery of their own native element. He completes the ritual, calling forth four great dragons.