I don’t know if what the creature did while piloting the shadow is a good indication of what the spell can do considering it also managed to perform magic of some kind to get them to the Spirit Plane.
That’s not to say your idea sounds implausable though. You can sacrifice blood and other parts of a human presumably. I think the biggest roadblock would be the skin barrier. I don’t think we have much reference for how strong it actually is though, so who knows if this is something she could do now or if she’ll need to get more powerful first.
The closest thing I can think of right now is Ana’s rending keychain and you need to stab that into someone for the spells to take. Maybe it would be easier if the shadow crawls into the target’s mouth?
I think it’s a combination of power (you can overcome barriers by throwing more power at them) and lacking the concepts.
We’ve seen how her shadow’s utility has grown in leaps and bounds with the correct conceptualisation.
Your point about it being able to open a portal to the spirit world could just add to that. If it can cut through anything, why not cut a path to other realms?
A hole that could presumably snap shut once the active absorption is shut off.
I’m a little shaky on how the underlying concepts would work, but I can certainly see that it seems plausible.
This could be really interesting, because who says it just has to be the spirit realm that she’s limited to accessing in this way? Planar travel may be in our girl’s future!
It’s possible, but only for esoteric/ritual type spells, not modern sorcery.
Personally, I would only try something like that if I had no other option. The air touching your lips would be likely to get either very cold or very hot, enough to cause damage to such delicate skin. And if you couldn’t keep your lips pursed in a good Circle the stability of the “containment” would fluctuate. If you accidentally close your mouth…you’re going to have a bad time.
But you wouldn’t be able to talk, which a lot of esoteric spells require, so the application would be very niche.
With esoteric spells, the energy transfer is kept inside the bounds of the Circle, and most are set up to remove the very excess energy they might leak into the air. With modern sorcery, energy flows through the bounding lines/the array, which in this case would be the flesh itself.