When you have Sponsored Magic, spells you cast with that magic must fall within the Sponsor's agenda; that limitation is why you get an extra 1.5-2 refresh of goodies with Sponsored Magic over taking Ritual + Channeling. For Hellfire, that agenda is specifically listed as "causing pain." Hellfire likes to cause suffering.
You have the
option to take Sponsored Debt, when you want to and when the Sponsor 'approves,' to
supercharge your spells. Sponsored Debt is effectively a mechanic that lets you take out compels on credit. You can get a +2 to Power or Control, or for some special effect, by taking a point of Sponsor Debt, and then have to take a compel later w/o getting a FP in exchange. The Sponsor decides if they want to actually give credit in every case. How many points of Debt you can have at one time is up to the GM, but it normally shouldn't get to be more than a few.
All sponsored magicks grant some kind of evothaum; that is, thaumaturgy using the speed and methods of evocation. Some interpretations of the rules say that every use of evothaum requires taking a point of debt, but I usually don't require that unless the PC is trying to do something particularly unique/challenging the scope of their magic.
An expansion of the Sponsored Debt rules many have house-ruled until the Paranet Papers introduced it officially is that you can incur Debt for any kind of roll or purpose, not just casting spells, as long as you're following the Sponsor's agenda. I like this idea as well.
(Perhaps a good homebrew rule might be that you could take a point of debt to use magic when the sponsor would otherwise be neutral to the situation?)
That works and I generally allow it. The whole idea w/ Debt is borrowed power, and getting temporary allowance to cast outside of the Sponsor's agenda is going to come with stings.