Magic in IC is channeled via etched seals, usually drawn on paper slips to be thrown or plastered somewhere, but you'll see a few carved on stone walls, bullets... even on weapons. Despite the seals not being terribly present yet, they do have a working system, which I've packaged in the seals guidebook that's attached to this post. :] This is a draft-ish booklet where some of the finer points may be tweaked as the plot demands - but overall - it should stay consistent.
For the tl;dr version - there's four Greater Seals: Keeper, Seeker, Reaper, and Watcher; originally holy magic made by humans to better arm themselves against demons, which have been a ~problem~ since forever.
Of course as humans break everything (lol), there was some different actions that were teased out from the original seals - positive and negative actions on one axis, and then passive and active actions on the other. I'll let the chart explain the differences there, but the key is that they can be chained together for some pretty complex Actions ... and not all of them as holy as they were originally meant to be.
here's a riddle for you patrons - what do you think Diane's dagger does, given the very particular seals on it? :]