The world of FM is technically the same universe as SHOS, but it operates on a different timeline and thus, counts as a separate universe.

Supernatural, fantasy

The magic system on FM is based on "wild" magic.

Magic has existed since the world's creation at the start of the universe and has existed alongside the universe forever. It is, by default, an infinite resource that has no repercussions for its use outside of what the person can physically handle. However, the life on Earth that has developed for the most part has never touched or accessed the ancient magic.

As life developed on Earth, magic settled into the systems as we know of them today, growing and evolving alongside the people and the various species to form into "branches" of magic with their own specialties and abilities no one else has access to. For example, although Mages have access to every magic "type", the types of magic they access are like the 'children' of the original wild magic that existed at the start of the universe. And if you want to think of FM as having "ley lines" like SHOS did, those ley lines are what remains of the original wild magic, and not the wild magic itself.

There exists pockets of the wild magic that remain from the time of original creation, trapped underneath the Earth's crust like one might find fossils or coal, located so deep underground that no one and nothing that currently exists on Earth can reach to it (even magic beings can't touch the sources). As eras go by, those few remaining pockets of "wild" magic leech into the world through its environment. There are pockets in most cradles of civilization (hence why they are cradles of civilization), and dotted around a few handfuls of other places as well.

Snow Haven is one of the more obvious places where it is known such a pocket must exist, because of the hot springs. Even though the magic exists underneath the geothermal waters and tectonic plates that give birth to the hot springs, the magic is strong enough to seep into the very waters themselves and lend power and mysterious energy to the land surrounding.