As I wanted, I keep unn certain mystery about the appearance of the Master, now we know that it is in fact much larger than Keerlyna and this partly explains the enormous size of her belly.
I do not think the Master is a kind of god of chaos, but in any case no power is not far. Keerlyna do not choose to carry babies from anyone
However, because you have, in fact today, it is expected that its gigantic belly take a few minutes: D (think back to the drawing that I've done with all these impregnated girls, you will have a good taste of her future size)
Once the babies into the world, a gathering of mages assesses their power. The most powerful are educated to war and are actually sent colonize other countries when they become mature.
Women are generally sent to temples where they become priestesses or magicians. Some stay with Keerlyna and are then part of her court. The rest of the babies, the less powerful serve to swell the ranks of armies.