I dislike sponsor debt with Soulfire

[Tedronai]

someone gave harry access to it. I think as long as Harry uses it as a good person would(with little abuse) he can keep it, should he turn dark or reaquire a coin he would lose it. All the fallen lost their access to it, it was replaced with hellfire. harry would be no different. I dont think his actions are controlled by Jake, but jake has taken a very very keen interest in his life. And soul fire has meant the idfference in a lot of the stuff that has kept harry alive. It wouldnt be a tool i would want to lose.

Someone gave Harry access to it, but I've seen no evidence that anyone is involved in ensuring Harry's continued access to it.  Even the direct WoJ doesn't say anything to this effect.

Perhaps Jake (or someone in that realm) would be able to take direct action to remove Harry's access, but there's a difference between that and simply the withdrawing of sponsorship, or some inherent passive kill switch.

[Theogony_IX]

I've decided not to run soulfire with sponsorship debt, but rather with a stress track determined by discipline.  I chose discipline partly because conviction was already used for the mental stress track, but also because building your soul isn't done simply by how much/strongly you believe, but by the actions you put behind that belief.  Bob didn't tell Harry to rebuild his soul by believing harder, but by doing nourishing things.  Nourishing things aren't always easy to do or fun to do and that is much more the case when it comes to the higher level spiritual stuff, and in those cases it's about discipline.

1 soul stress to perform an evothaum spell if you allow evothaum with Soulfire, 1 stress per point of power or control.  The stress track doesn't clear at the end of every fight though.  You have to spend time and make rolls to clear stress. I figure 2 points of stress per declaration.  Time frame for the declared action is negotiated between the player and the GM, but it should be fairly common sense.  Extra declarations can be made for longer actions.  For example, a whole day of meditating might clear your 1, 2, and 3 soul stress boxes, but dinner with a friend might only clear your 2 soul stress box.

Since soul stress boxes don't clear as quickly as other stress boxes, you only need to use those boxes when you perform evothaum, and when you're calling up power/control above what comes naturally to you.  It works very similarly to debt, but reskinned.  Debt to absorb stress, and debt to invoke aspects for free, but in this case, you're using a stress track you need to actively clear rather than debt and compels.

Feel free to critique.

[Sanctaphrax]

Sounds too powerful to me. Sponsor Debt is minor enough that you can hand out the ability to take it for free without breaking anything. This...isn't. It's a free +10 (1+2+3+4) that recharges every time you have a chance to relax.

[Theogony_IX]

Like I mentioned above, the soul stress track doesn't clear like other stress tracks.  You have to invest time into resetting it.  If the story is fairly fast paced, you shouldn't really be getting the kind of time you'd need to reset it completely.  You could possibly manage to clear 4 points in a tense story, but in Harry's stories, even sleep is hard to come by and I try to build my stories the same way.  Resetting the whole stress track mid story should be uncommon.

The 10 points of stress equates to 5 sponsorship debt.  That doesn't seem unreasonable as a credit limit for sponsored magic.  Also, you can't take a few compels over a couple scenes to reduce that quickly before the big show down.  With this set up, you have to be more careful of how you spend it during the early stages of the scenario since you may not get the time to invest in rebuilding your soul.

[Sanctaphrax]

Actually, you don't need to be careful at all. Nothing bad happens when you fill your soul stress. You get a bonus, and in exchange you don't get that bonus later.

Whereas with Sponsor Debt, something bad happens every time you use it. 5 Compels is brutal. Potentially enough to make you miserable for multiple sessions.

Also, it's not good to make mechanics that will randomly snap the game in half if someone paces the story unusually. Frenetic action is the most common way to play DFRPG, but the game actually works just as well with one scene a day.

[Theogony_IX]

Well, I modeled it as closely as I could to the way Soulfire works in the books, and so far I haven't seen anything to suggest it works any differently than the way you just described.  I catch your meaning though.  The way it works in the books may not work for a game that relies on balance.  I still like the idea of a stress track to mark the usage of your soul to feed your spells, but I'll give it some thought and see if I can find a way to give it some teeth.