Okay, so I recently found my Chaosium copy of Masks of Nyarlathotep and Fate Core is all new and shiny, so I decided to give it a try.

Aspects:
High Concept: Yeah, I like the DFRPG term better
Trouble: As normal.
Pillar of Sanity: I liked that idea quite a bit. "Why aren't you insane (yet)" seems like a question that needs a place on the character sheet
Adventure: Your "pilot introduction scene," where you get to show off what makes your character interesting.
Guest Star: Where you describe what you did in someone else's Adventure scene.

Skill List: Academics (renamed from Lore), Athletics, Burglary, Contacts, Crafts, Deceive, Drive, Empathy, Fight, Investigate, Mythos (New skill), Notice, Physique, Provoke, Rapport, Resources, Shoot, Stealth, Will.
Design Notes: I don't want to bloat the skill list unnecessarily. PCs will only have 10 skills [assuming a pyramid with a cap of Great (+4)] and 3 free stunts at character creation, so this way they'll have just about half of the skills trained, which seems right to me.

New Skill: Mythos
Overcome: Understanding Mythos books, inscriptions etc.
Create Advantage: Recognize monsters, spells, rituals, significant constellations etc.
Your Mythos skill is also the Weapon Rating of all mental attacks from Mythos creatures and knowledge (you'll typically defend with Will against this, incidentally). Damn your luck.
No character can start with the Mythos skill, unless the GM (AM for Asylum Master?) rules otherwise
Attack: Only with the Ritualist stunt and an appropriate spell.
Defend: No.
Design Notes: Basically, understanding stuff is free (though it will take some milestones for characters to get a significant Mythos skill), but using spells costs a Stunt (making the cost for spellcasting 1 skill + 1 refresh; no need for a character aspect, the campaign aspects undoubtedly have that covered). As people learn more about the Mythos, however (as they increase their skill), they enter the rapid down-spiral of growing more insane. Yay!

Spells:
As Void Calling (from the Magic systems extra), but with additional spells.
Important points:
  • Magic is easy to do and powerful, but hard to get right. Even a flawless casting (ha!) will have negative consequences.
  • You need a spellbook (notes, inscriptions, whatever) to use the spell. No way you can memorize these things; you're only human.
  • As you succeed with style (well... if) on castings, it becomes slightly easier to decipher the rituals. Remember, the difficulties listed for the spells is the minimum rating. You might get some garbled mess written by some insane cultist, where a Fair (+2) spell is so poorly copied that you need a Legendary (+8) roll to cast it properly (and +11 to succeed with style).

As for the existing spells
  • The Dapper Gent: Probably Nyarly himself. Always glad to lend a hand, but never quite for free.
  • Wound-Eating Beetles: Yay, healing spell! I'm sure that whole "might lose your connection with the world" won't ever be relevant, right?
  • Lazarus Eyes: Hey, a resurrection spell! I'm sure it doesn't have any horrifying side-effects.
  • Lightning Worms: Finally, a blasting spell that doesn't have the potential to create more problems than it solves. Entirely unrelated, this also works as Create Zombie... though there should probably be a Control Zombie spell somewhere. Ah, I'll leave that for later.
  • Mineo Toadstool: Disease isn't a big threat in most CoC games, so I have no problem with how this is genuinely an "I win" card against disease. How it leaves a wake of pestilence in the wake of the PCs is just a bonus.
  • Freet: Call it a Fire Vampire and you're done.

When adding in the many CoC spells (and, honestly, a lot of them don't need to be), just remember that a good casting needs to be a bit inconvenient and a poor casting can have horrific consequences.

Thoughts?