sponsored magic

[PirateJack]

Who does the compeling

For sponsor debt? The GM. He is the voice of the sponsor so he is the one that tells you what the offer is.

[potestas]

For sponsor debt? The GM. He is the voice of the sponsor so he is the one that tells you what the offer is.

if its self sponsored who does it then

[Sanctaphrax]

The GM.

[Haru]

I would say that in addition to the GM, the rest of the group can suggest compels as well, though the GM is still the arbiter.

Remember that the compel is a mechanical thing, not a narrative thing. It lines up fairly well if it is an external sponsor, where "Your sponsor forces you to..." lines up with "The GM forces you to...", but that's only one way to interpret this. Even with an actual sponsor, it doesn't have to be a scene like "I'm your sponsor, and now I tell you what to do". It can just as well be that the magic the sponsor gave you in itself is changing the way you think and leads you to make decisions you wouldn't normally do. That's a compel right then and there, it is choice taken away from the character, he just acts according to his nature. And when it comes to self sponsored magic, that type of "nature vs. choice" type of compel will be the one you'll use most. It's actually one of the big themes of the dresdenverse as a whole.

[potestas]

The GM.

were is the rule that allows GM to do it.

[Hick Jr]

were is the rule that allows GM to do it.

Self-Sponsored Magic debt is handled the same way that normal Sponsor Debt is handled. The actual power is below.

SELF-SPONSORED MAGIC [-Varies]
Description: Either you’ve studied a branch of magic long enough to understand and use it intuitively, or you’re a being of such singular power that a unique form of magic emanates from you.
Skills Affected: Conviction, Discipline, Lore, others.
Effects:
Self-Sponsored Magic. This Power is in all ways identical to Sponsored Magic, except that it lacks an external sponsor. The Compels resulting from the debt taken to fuel this power are therefore obviously not connected to any external agenda; instead, they are linked to your Aspects like normal Compels.


As it says, they're linked to your Aspects and are treated like normal Compels. However, as someone (I think it was Haru) said earlier, it might also involve themes of the magic itself- Self-sponsored Wards Magic would Compel you to be cautious and defensive, Shadow Magic would Compel you to be sneaky and deceptive, Fire Magic would compel you to be energetic and chaotic, etcetera.