Void Sorcery

Void Sorcery is entirely distinct from Aiaosian Magic, calling directly on the power of the Void. It is wielded by Outerfolk arcanists - who are actually few and far between; most outfolk despise magic, favouring instead arcanotech and the mental powers known as psionics - and by Aiaosion warlocks and sorcerers whose power is drawn from the Void.
Void magic granted through pacts is not greatly different from that granted by more benign pacts. There is always a cost involved, but it is rarely direct contact with the energies of the Void. Sorcerers whose power comes from the Void are a different matter.
Usually born in areas of high Voidspar contamination, their powers actively harm them. Each time they draw upon their magic, it erodes a part of their mortal, worldly flesh or essence. This creates 'scarpaths' - hollowed or transformed parts of their self that are left resistant to further corruption - but the use of the power is never without consequence, and the greater the power drawn, the greater the consequence.
A sorcerer who uses Void sorcery incautiously will ultimately find themself more of the Void than of the World, flesh transformed either to the corpus of one of the outerfolk, or even to pure ifril. These transformed body parts act as powerful magical foci, but also a source of constant pain. Worse is the harm to the sorcerer's soul, which may become so distorted as to no longer be for any god of Aiaos to claim, and fall ultimately into the hands of the Colossus who gave them their power in the first place.