[@Necromancy] Demons come from the Underneath (very creative I know) it's literally a system of caverns miles below the surface.

the Taerin are a cross between elves and dryads.

magic is a simple structure for the use of the 4 base elements. most people tend to have at least an elemental affinity if not the ability to cast spells.

I haven't considered lesser factions, however I guess branch factions would have to be the case as those are a common occurrence.