I like urgency. I like conflict even more. A story or setting without either bores me. 

But we can get to that. Hmm.

"Following a major magical incident, the people of the Homeworld are forced to flee to the off-world colonies"?

I'm thinking, but not yet writing into the premise, that the colonies might have been subjugated by the Homeworld. That maybe the Homeworld has oppressed them, and that the current situation grinds some gears.