Geological / environmental event
The world is beginning
Druids refine the environment for survival of humanoid life. Mossy beds covering miles that later bloom into mighty forest and spawn mighty guardians. Geomancers rekindle the planet core. Slowly cutting lifeless stone and imparting friction and heats to warm the heart of the world. Ships gather icy asteroids. Using the three moons as staging points to gather and accurately drop large icy space rocks into low lying regions to form seas.