Help making Powers and Threshold Magic work together

[dataweaver]

Originally Posted by Varyon

I'd need to look back through Horror (and Thaumatology for that matter), but I'm pretty certain Corruption is a lot worse than Threshold. IIRC, Corruption doesn't really go away on its own, you need to basically perform good deeds or receive absolution from a higher power or something similar to erase it. Also, instead of getting too much of it risking a (minor at first) Calamity, getting too much automatically results in you basically losing character points in the form of gaining appropriate Disadvantages.

Following the section which I cited, there's an example Corruption system, which is not definitive; it's just one way that Corruption can be implemented. Using Black Magic as a basis for Corruption is equally valid, as are using Assisting Spirits or Threshold-Limited Magic — though if your intent is to use it to represent the “power corrupts” idea, you should probably tailor the Calamity Table in much the same way that Thaumatology has tailored Critical Fail tables to represent different flavors of magic. But while the section is couched in the concept of magic being inherently evil, the concepts presented in that section are less about that and more about matching systems of “paying the price later” with systems for representing non-human abilities other than magic. I would know: the section that I'm referencing is almost verbatim text that I submitted during the GURPS Horror playtest.

The Corrupting Limitation was proposed by another playtester, whose main motivation seemed to be that he didn't like how “Costs FP” adjusts the cost of the ability proportional to the Ability's cost, but doesn't adjust the FP cost in the same way. That's why the discount if Corrupting is only nominally –20%, and is in practice proportional to the number of Corruption points generated. It wasn't about “Corruption is harsher than FP, so it should be worth more as a discount”.

The Sample Corruption System came from a third playtester, who wanted there to be suggestions for how to gain Corruption other than power use. It also provided its own guidelines for the price you pay for gaining Corruption and the means you use to get rid of it, essentially defining another system that parallels Black Magic, Spirit Assistance, Threshold-Limited Magic, and Point Debt. In fact, it parallels Point Debt in much the same way that Black Magic parallels Spirit Assistance.