Basics
This is an alternate campaign model for the Ars Magica game, one which adds a mysterious threat while keeping the theme of the Order and its Magi in many ways the same. I'm posting it here not because Ars Magica is boring in canon but because the setting has so much potential to be shifted and morphed into various other possibilities. Also, I figured others might enjoy the concept I created here and so I felt like sharing it.
Introduction
What first made the Order aware of the approaching great danger was when two covenants went went silent. Investigations of the sites couldn't find any signs of the magi, but the ruins did seem to indicate that the end for them was quite horrific and quite unnatural. Not much more was learned and so most magi began putting the events aside, just another mystery to add to the many that the Order knew about. It was only a few years later when a maga from a third covenant appeared at a Mercer House asking for asylum that the first true ironclad evidence that a mysterious dimension spanning war was going on in the background. The maga had with her magical recordings and solid evidence of the acts propagated by two races when they assaulted her covenant, of which she was the only survivor.
From this moment the Order became aware that two races were engulfed in a shadowy war across all of time and space. That this was a war going on for millennia and though broken up into periods of cold war it had just suddenly became hot again. What was even worse was that Earth itself was the battleground, for the two forces could not fight in their own home realms, for reasons that were not immediately obvious. No names or true identities could be determined, though all signs did point to each having a purpose - one was dedicated to Chaos and Creation and the other was focused on the path of Order and Destruction. But even more to the point, the two forces hated each other with a burning passion that seemingly knew no end.
To really make matters worse the Earth was right smack dab in the middle of the war. Mythic Europe was the battlefield where the two forces would and could fight each other without either having any hometurf advantage. While many elements of each race was unknown, it could be determined that entrance onto the Earth could only happen through certain proper points in space and time (often made easier if gates existed at said location). It was quite clear from the onset that mundanes had no hope of fighting or stopping the two forces, though thankfully the same could not be said for the Gifted. The potent spells and rituals of the Order of Hermes did work and could be used to resist, stop, or destroy the forces of both factions. At the point where the campaign starts neither Faction seems to truly be aware of the magics of the Order and so do not consider humans or the Earth to be a threat, a fact which provides the Order time to make plans.
Cosmology
Reality is a multifaceted phenomena. There are currently three main Realms as well as a host of demirealms (regiones) that seem to exist around them.
The first main realm is that of the Earth (or Mythic Europe at this time), a place naturally of the mundane and the natural. It is considered the middle realm, but it is also the oldest of the realms, for it has existed since primordial times, even before the other realms existed. The Earth is special in that any and all beings can live and survive on it, the Gifted of Magic or the two fighting forces. It is for this reason that the two dynamic enemies fight on the Earth, it can sustain them just like their own realms can. The supernatural in this realm is Magic laid up on top of the natural.
Arrayed around the Earth Realm are the individual realms of the two warring powers, one for the Chaos/Creation race and the other for the Order/Destruction race. The two aspected realms can house a being native to the Earth, but cannot sustain a being aspected towards the opposite realm. This means that why a human, even a Gifted one, can go to the Realm housing the Chaos/Creation race a member of the Order/Destruction race cannot sustain themselves in the Chaos/Creation realm.
Realms of Power
Though it is completely possible to keep the normal organization of the Realms of Power (Magic, Faerie, Divine, and Infernal) the same, I would consider it better to change the way the metaphysical landscape of the game works.
In this version of the game Faerie represents the race that is Chaos and Creation while the Infernal is that of Order and Destruction. Thus both sides are pretty bad.
That which is officially in Faerie but considered traditionally good or player-friendly can be rolled into Magic, which as always is the realm of power for the Gifted and the Order of Hermes. This means that many of the faerie creatures are actually Magical creatures in this version.
The Divine represents the unique and special power that has no true explanation but that can seemingly cut through all other powers. In a mythic sense it could also represent the First Race, the mysterious race that seems to have existed before and maybe even created the two fighting foes.
The nature of this change means that one cannot actually normally go to the Magic, Faerie, Divine, or Infernal realms. The Magic realm is at this point in time just a layer of mystical abilities added ontop of the normal Earth. Faerie and Infernal are realms where the enemy powers who are fighting each other lie. While the Divine is something special, unique and where the gamebreaking special features are placed.
Characters
The characters of the game are the Gifted. They may (and are designed around being) of the Order of Hermes but they could also be from any of the other eclectic magical societies. The point is that while mundanes and normals only die when faced with the warring forces the Gifted with their spells and rituals are able to fight back and even win.
Campaign
The world of Mythic Europe of this variant campaign is almost entirely the same as normal. The almost entirely is because everything in the past remains the same and can be used withiut alteration (just add a mysteriously fallen covenant or city here and there to represent the fighting of the two warring races). In the recent past knowledge of the hidden war has begun to grow amongst the magical population. This hasn't stoped internal conflict but it is starting to change the focus on things.
Exploration of long lost sites are still common, but now its done to see if they have any information about the Shadow War and the forces fighting it.
Research still occurs, and while a lot of it is still to better oneself and covenant it also has taken a marshal and defensive tone.
Politics is still ongoing, but its now what should the Order and the Tribunals and the Covenants and Magi do about the warring powers, the mundanes, and the other elements of the supernatural.
Themes
The campaign is not about loss of hope, or feeling that the world is gonna die and there is no hope or reason to live anymore. Its about people seeing that their magics can do something and then deciding that they are going to do something. And then looking around to figure out what they can do, and then doing it. Its about banding together and trying to create something that could either stalemate the war, stop the war, or even get the Earth out of the war entirely.
Possibilities
The realm of Earth at this time is where the two forces fight because both can live on it without any weakening of their powers. This is because of the Magic that infuses the whole of the realm, a supernatural that is baiscally layered ontop of the normal and the natural and the mundane. But what if the Gifted (such as the Order of Hermes) found a way to take the Magic from the world and spin it off into another Realm, a realm of Magic for the Gifted and the supernatural of the Earth. It would be an equivalent Realm to the ones that are now the homes of the two warring factions, and would work to change the face of that war entirely. With the Earth no longer be so delicious to the enemies the mundane populations could live out their lives in peace, while the magical population (both Gifted humans and supernatural creatures and plants and spirits) could go to their own place and live their lives in a society without having to worry about what the mundanes think.
Notes
Need a better name for the two warring races other than Chaos/Creation and Order/Destruction. I do not want to call them Fae (or Elves) and Demons.
Closing
I would enjoy any feedback or constructive thoughts one might have on this. I'm not saying I would develop it further but well if there is enough interest maybe a collaborative project could be made, who knows.
Till next time!