Necrothread!
I almost did a new post, titled "In defense of Mythic Blood", but then, I figured it's best not to clutter the forums, so here I am.
I wad thinking about MB yesterday. This is a virtue I've always loved, thematically, but hated mechanically: it feels as though the innate power and the focus should be similar, but there's usually no power that can't be replicated within the focus, given a few years time.
So, in my upcoming saga, we have a verditius with MB: Alberich (king of the dwarves in the nibelungen saga. Their innate power is invisibility, and their focus is in enchanting golden rings (this is my solution to the "enchanting foci" problem: it only works for enchanting, and, if minor, it must be limited by material and shape, like wooden wands), which fit the theme nicely
But the other night, I realized the " spend no fatigue" is actually pretty good: One can expect casting totals to be close to one's spell levels. So, with this, you can actually afford to cast silently (or with no gestures and quiet words) for free , which my be quite useful if you're operating amongst mundanes.
So, all in all, MB turns out to be a better virtue that what I thought
Granted, this one takes some research, but Potent Mythic Blood is a potential integration project from the Muspelli, giving those with Mythic Blood what is essentially Ettin-mod / Inner Heartbeast (A form more powerful then their base, physically and magically. Presumably with added ways of further refinement)
That and it gives access to Heroic Virtues & Flaws.
Side note, there's "magic blood" in BS&S, in the Tangiers section, and a whole lot of Mythic Blood suggestions in a number of Sub Rosa issues that I spun up, for those wanting other references.
I might be influenced by 4th Ed, where the ancestors of Gifted people can all be traced back to the mighty magicians of pre-History.
Bonisagus might also have been a follower of that idea, and Hermetic Initiation is designed to try to call forth the Mythic ancestral powers.
The problem is, the ancient bloodlines are too dilute, and the best that Hermetic Initiation can do is occasionally bring forth the Mythic Blood of a more recent powerful wizard.
In this scenario Mythic Blood doesn't appear until after Hermetic initiation.