I'm interested in the temporary power/sponsor debt mechanic as a GM. Can you give me an example of a WCV using his powers and then what happens next using this mechanic?
How I'd run it: most of the time, you just use whatever powers you've paid refresh for. Let's say you have Inhuman Speed on your sheet - if you use that in a scene, then you get some of the WCV visual effects (silver eyes, etc), because you do still have a "human guise" power - but the resulting hunger isn't overwhelming; your normal feeding habits (whatever they are) are enough to cover it.
But say you need Supernatural Speed for a scene. Well, that'd cost two refresh - refresh that you don't have (or don't want) to spare; so instead, you pay for that with two points of sponsor debt. You get Supernatural Speed for the scene... but it's going to come back to haunt you; at the simplest level, you could skip the next scene (because you have to go feed now), or you could kill some random unimportant mook - either of those would probably pay off a point of debt. Rack up enough debt, though, and the GM is going to start getting evil with it - having you kill or cripple someone you care about, for example, or changing one of your aspects appropriately (which could go either way, really; a loss-of-control incident could promote either "Mortals Don't Matter" or "Afraid Of My Powers", depending on what direction the player wants to take the story.)
Another example of a one-point compel might be just visibly starting to lose control in front of your friends - even if someone like Mouse steps in and makes you back off, that still puts into play an aspect of "Can We Trust Him?" or the like.