I find you missed a few things with the Aedra. Now, I might bewrong, but here's my understanding of it; So this part wasn't a mistake, but is worth mentioning, that stars are holes, through which the Aedra left, when they opted out of Mudus' creation. This is the part I think you got wrong; Magnus didn't agree to any of this, and also tried to leave. However--and I forgot why--but he couldn't, and so the hole he tried to leave through--the sun--was much bigger, and part of him was left behind on Mundus, and harnessing those remnants created Magicka. But, I might be wrong. Been forever, since I studied up on ES lore.