CoC-Style Magic
 

I'm new to the GURPS system, so I hope this isn't a naïve question, but I'm wondering if the GURPS magic system can accommodate a Call of Cthulhu or Elric magic paradigm. That is, a magic system that is difficult to execute, time consuming, and dangerous (possibility of demonic possession, madness, etc.).

If so, which source books would I need?

Re: CoC-Style Magic
 

Yes it can.
I discuss most of the systems here and link to a few others, such as Rogers blog who recent l had a similar discussion.
In particular if your looking for a POW or SAN mechanic the article The Fifth Attribute from Pyramid #3/120 Alt GURPS V is similar.
Corruption from GURPS Horror has a Corruption mechanic for converting most systems to a dark magic kind of thing. Horror is likely to be a lot of use in a dark type campaign.
And GURPS Thaumatology has Spirit Assisted and Threshold magic along with lots of ideas for tinkering with other systems.

Re: CoC-Style Magic
 

And GURPS Cthulhupunk contains the conversion rules for CoC to 3rd Edition GURPS, if that's of any assistance.

Personally, I'd also get the Thaumatology - Sorcery supplement. Most of the CoC spells are closer to that in feel than the default magic system or Path Magic.

Re: CoC-Style Magic
 

Welcome to GURPS, Ezra. GURPS is a great system for cosmic horror, and it can absolutely accommodate CoC-Style magic. Since the genre depends heavily on various forbidden tomes, I'd recommend you use Ritual Path Magic (detailed in the booklet of same name), and only allow rituals that you, the GM, have defined in advance and associated with individual grimoires. It is a very versatile system, and the PDF book is inexpensive. And, characters who dabble in magic without knowing what they are doing can wind up having their ritual blow up catastrophically. OR, use Path/Book Magic from Thaumatology. Either way, give each casting a cost in terms of stability (GURPS Horror), and you ar close enough in feel.

Re: CoC-Style Magic
 

Another possible solution would be to use Energy Accumulation Path/Book Magic with threshold replacing energy (the rules for both are in Thaumotology). In effect, you create a slow and subtle form of magic that strains the fabric of reality. The spells from CoC could form their own Books and the relevant core skill would be Ritual Magic (Mythos).

Re: CoC-Style Magic
 

That Corruption mechanic sounds perfect. And I already own GURPS Horror, actually. :-)

I'll need to purchase Thaumatology, but I need to do that anyway.

Re: CoC-Style Magic
 

I'll need to obtain both of these sources, but it sounds like I'll need to anyway. Thanks!

Re: CoC-Style Magic
 

So it sounds like the resources for this style of magic are the following:

• GURPS Horror
• Thaumatology
• GURPS Thaumatology - Sorcery
• GURPS Cthulhupunk
• Pyramid #3/120

Thanks for the help everyone! :-)

Re: CoC-Style Magic
 

In one of my campaigns (The Awakening) I modeled CoC magic using Ritual Path Magic and had each spell cost a certain number of Stability Points (from my Article "Mad as Bones" which is a way to model sanity points from CoC). Specifically, the greater effects multiplier was the number of SP lost from casting the spell. It had other rules too like if a spell brought you into negative SP all sorts of ugly things happened.

Re: CoC-Style Magic
 

Found it Pyramid #3/103