The Nature of Magic

Magic is a fundamental force of nature, analogous to gravity. But where gravity is most strongly aligned to Earth and Water, granting those materials weight and substance, magic is most strongly aligned to Air and Fire, granting those materials heat and motion. But where gravity is simple and rigid, granting a constant amount of weight and substance, magic is complex and dynamic, granting a constantly growing amount of heat and motion to Air and Fire and then taking it away. With fire this ebb and flow is still fairly slow and controlled: the sun's fire brings sudden heat at the dawn of the day and it ebbs away at night, a campfire grows quickly when properly tended, and slowly fades as it dies down. And with air, the energy builds, and then suddenly discharges, and it is these discharges that have defined life in the world of Irion.

Harnessing Magic

Magic is the force of heat and motion, and is incredibly malleable, responding to thought as clay to the potter's hand. There are many disciplines for manipulating it, from the rigid formulae and focuses of the wizard to the instinctive dabbling of the sorcerer to the boons of powerful beings weilded by clerics and warlocks, but no matter how one taps into it, it is all the same force. Those who work with these forces are known as Magi, and generally well regarded in society - both out of a tradition born from gratitude for what great Magi have done for the world millennia ago and for fear that an angered Magus might turn their abilities upon the source of that anger.

Tiers of Magic

Controlled magic is categorized in 11 tiers, based upon the amount of latent energy required in the air and upon the amount of mental fatigue brought on the Magus casting the spell. The lowest of these tiers is formally known as the zeroeth tier, though these spells are more commonly referred to as cantrips - simple exercises in control that any Magus can cast as many times as they wish without showing any sign of strain. In most cases, an aspiring student or self taught prodigy will cast one of these as their first spell; many remember this first brush with the power of magic fondly, even decades after mastering substantially more powerful magics.
The following nine tiers are collectively known as Low Magic. This does not imply they are unimpressive - indeed, even spells of the first tier can have a dramatic effect, and those of the ninth tier can be outright miraculous. Low Magic is magic that can be cast in areas protected by an Anchor, a magical device that draws in excess magical potential to mitigate the damage that might otherwise occur.
The final tier is known as High Magic, powerful and exhausting rituals of magic far beyond what Low Magic is capable of. With High Magic, a molehill might be made into a mountain, quite literally, and with the mole enlarged to match. The most legendary example of High Magic is the production of the Archmage's Stone, a powerful magical device that operates both as a sign of status and an aid in casting lesser magics. Soldiers returning from the Great War, however, tell darker stories - of High Magic being used to slaughter whole armies, or to make the dead from either side rise up and fight for the caster. A Magus who has demonstrated sufficient skill to wield High Magic is granted the title of Archmage, and accorded the great honour and respect due to one of the most accomplished and dangerous Magi on the planet.

Magical Storms

When left to its own devices, magic builds up in air and then discharges rapidly, in an event known as a Magical Storm. Normally, a Magus wielding magic must draw in that magic in order to shape it with their thoughts, but in these events the magic comes all on its own, flowing into anything capable of thought and taking shape from any stray thought. Sometimes this is beneficial - there are stories of mortally wounded warriors in the wildlands suddenly recovering completely, rising and returning to life as if nothing had happened - but often it latches onto the darkest of fears. Beings of nightmare come into being, brought in from a variety of realms where such creatures dwell. The dead rise en masse with an all consuming hunger for the life they can never regain. Catastrophic earthquakes tear the land apart.
Before Anchors were developed, people lived a largely nomadic life, hunting and gathering supplies as they traveled, never stopping in one place for long. Some discovered seeds would grow into plants, and thus developed agriculture, but with the threat of these Storms, they could never stay in one place for long enough for their labour to bear fruit. Magi were a common element of these ancient societies - people who fought to control the Storms, turning magic itself against the Storm-birthed monsters that threatened them. Even Archmagi were common, often leading individual tribes. It was one of these Archmagi who eventually developed the Prima Ancora - the First Anchor, and with it, the first refuge, the first hope for a better life.
Meanwhile, deep underground, the Anchors brought devestation. Down in these caves, there is less air for magic to develop in, and thus Storms are less intense. Down there, the first cities had been built centuries before, with High Magic wards being sufficient to protect the cities. High Magic wards that faded as the Anchors were built above, sapping the magic needed to maintain these wards just as it sapped the magic from the atmosphere on the surface that maintained the threat of the Magical Storms.