Magic is useless.

The only spell which exists is a ripoff "magic missile": it doesn't hit 99% of the time, and if it does, it's only over a short range on a very large target. Moreover, each use requires some form of sacrifice—you'd lose a finger to muster the force necessary to open a light door, or risk going insane.

This is the tale of a former urchin turned mage who has no avenue to continue living without magic.