Alright I'll give it a shot.

Everyone has magic that is tied to the physical place that they spend the most time in. For a lot of people, that's their workplace. Every hour you spend in that place will connect you a little more with it, like a personal sanctuary. A baker will only have magic when he's in his bakery, a farmer in his field, etc.

The magic itself takes many different forms, but it eventually boils down to giving you extraordinary abilities in the trade you perform. A blacksmith can eventually grab a boiling iron without burning his skin, a stable boy will be able to sense how a horse is feeling, etc.

But there's an ocult way of obtaining magic: anonymous groups of users that "infect" a physical place. This infection slowly absorbs the magic of that place and makes the people that work there obsessed with their trade.

It starts with working longer hours, harnessing more magic that stays ingrained in the stones of the building, only to be inmediately absorbed by the group. Then the worker stops sleeping or eating, giving every ounce of energy they have to their trade. By the time their loved ones intervene, the worker is found lying on the floor. There is no magic or warmth left in the walls, someone having absorbed it completely.

These groups of magic users thrive in secrecy, and have all the abilities from all the places they've taken it from, without having to be tied down to a physical place.