[@shagranoz]
Oh Boy

Well first off you didn't use any of the coding I provided for the sheet. Which isn't the biggest problem with this submission but I highly advise you fix that among other things.

This isn't your fault, but I already have someone working on a witch that is the daughter of Morgana. Which isn't too problematic as it is, in fact her's has her heritage a bit more distant so you can easily pass it as a long lost sister, but once that sheet gets over here I advise the two of you collab to avoid any lore inconsistencies. (In hindsight having an rp with Camelot as a central figure, I probably should have expected something like this.)

Her personality and heritage makes her, an unlikely candidate to be a Knight of Evil. Not that Lancelot doesn't enjoy his knights fighting over each other, but her world domination part is certainly a contradiction to what Lancelot idiolizes. Granted, she could keep this part a secret and just use this position to her advantage, but I'd like to emphasize if that ambition is found out; it can result in her death or exile.

Speaking of which; "Complete Immortality- Medea has developed a ritual that ensures that, no matter what abuse her body and soul endure, she will always survive. A favorite tactic to induce her opponents to surrender is to simply stand in front of them, letting them see how futile their assaults are. Note, however, that extreme methods of "death" like burning and scattering the ashes may take years to recover from"

TO be fair, there are plenty of hax spells that can bypass this, however having this form of immortality with the power she already has seems a bit much, especially when she doesn't really give the vibes of a true necromancer (despite having many necromancy-ish spells; something I'll get into later down.)
It would be much more reasonable to suggest that she has achieved immortality age-wise, and this can maybe include a resilience to diseases and a minor regeneration factor to still give her some survival abilities.

One of the biggest problems I have with this sheet is lack in consistency. You emphasize her abilities regarding hell's demons, yet you also give her generic necromancy spells to boot that don't really give the idea of flow. Yet she also lacks any variety outside from necromancy and demon magic, the overall feel of this character severely lacks in flavor. She is also a witch of Morgana La Faye, someone who was far more famed as an illusionary or Enchantress and seldom had any dealings with demons.

Speaking of which, demons aren't usually creatures ready at service. They are out for their own goals, and any deals made with them don't come without price. Liliana from MTG is a good reference for dealing with demons if you want to go that route, her necromancy and dealings with demons are much more in flavor and I certainly recommend giving her a look for inspiration if you want to continue this motiff.

Soul swallower I'm also a bit torn on. I like the idea of having an interrogator but having her permanently absorb a soul, as well as gaining a vague permanent buff from it; really seems a bit too...much. 

Before I get on with balancing recommendations, your sheet is very barebones. If you look at one of my NPC's for instance you will see that many of the information provided is much more fleshed out, while some of the important information on your end seems barely fleshed out. Her bio alone is only a few sentences. Don't take this the wrong way but I don't think you're cut out for a roleplay on the High Casual spectrum.

IF you are serious and willing to keep working on a sheet however; I recommend either starting from scratch or at least cut out most of things here and start over. To your credit you do have some interesting ideas here.

For instance instead of soul swallowing, she can either imprison the soul in an inanimate object to 'animate' them in a cursed form (As part of torture/interrogation.) Or she may offer this soul to a demon to help fulfill the idea of paying a demon for its service. Once again this shouldn't be the only cost for working with demons, but it is something I'd recommend.

If you can really sell the ideal that summoning demons has a lot of detriment consquences and costs, then the Book of Azatoth will work much better as an artifact. 

Sorry if I'm a bit hard but I do try to keep things in my management consistence and of quality; So this submission is rejected.