Here is the scenario:
In a fantasy world filled with orcs, dragons and other magic critters, most countries live relativly simple, as magic provides most things to life with strong king or other sort of goverment.
But there is one city on the continent, that had found something more valuable than gold: natural swamp gas. It burns hotter than coal, is cheap to extract and just slightly dangerous.
Thus a giant city grew in the middle of the swamp land, growing up in 4 giant towers build like gigantic christmas trees of metal, while lower branches sink into the ground, they just build it up slightly higher than before.
As the industries grew, many people came to work here and find their luck, even many mages to provide their services to those without the knowledge of the arcane. Even they everyone knows, metal and magic are a no-no.
Magic can be used to archive everything, but may take a was amount of effort, time and mages. So more complex things like creating "life" would take at least a lifespan of a mage to cast. So Golems exist, but may take several years to be created.
Magic is based on "free energy", that can be formed and restructured to useful effects
- The size of a magical effect is proportional to time a caster uses to cast a spell, OR is very dangerous and can cause demonic invasions.
- Magic is hindered and even prevented by metal, especially moving metal, but can't change the effect wished for.
- The industrial state is mostly steam engines with the twist of the use of swamp gas or coal enriched with swamp gas.
In this industrializes city, mages work and offer their services like fortune telling, healing and even teleportation (while extremly dangerouns in this city), but what jobs could a mage have in a factory as worker or other role?
Additionally, you can even give crazy arguments like "to lit fires in the smellting oven" (only job i came up with), cause mages accept every job as being very desperate and factory owners ignore dangers with possible "good ideas" for more profit.