This article describes an amalgamation of the World of Greyhawk and the Ars Magica game system. Much liberty was taken with both works in order to bring about their union. It was a short campaign that I ran back in the 1990s, using 3rd Edition Ars Magica.
A Quick Overview
The rest of this article gives a quick overview of the setting, and the changes that have been made.
The World of Greyhawk
The campaign is set just after the Greyhawk Wars, in the time detailed in the From the Ashes sourcebooks. Since a certain company who shall not be named seems content to let further detailing of this wondrous land fall by the wayside, I guess any changes or additions to those supplements that I add herein will not be contradicted in the future.
The Order of Hermes
The continent of Oerik, is much larger than the Mythic Europe setting of the Ars Magica game, and the rationale behind the Order of Hermes doesn't quite fit into the Greyhawk setting. The people are far too varied, disorganised, and dispersed for any single union of Magi to ever have control.
Because of this, the Order of Hermes is not as important to Greyhawk as it is to Mythic Europe. Magic is a lot more common, and a lot better accepted, amongst the common populace, so control over the actions of magi is not required. Further, the various religions are all far too preoccupied with fighting amongst themselves, to worry about magi.
Basically, the Order of Hermes as it is in the Ars Magica game does not fit well into Greyhawk. But it's stamp on the magic system is too deep to just ignore it.
The Order exists, though does not control the actions of all magi. Indeed, its presence is only strongly felt in the Kingdom of Aerdy, and even there it is somewhat different to the Order as described in Ars Magica. Given that Aerdy is closely allied with the Infernal, so the Order in Aerdy similarly has many ties to that as well. The centre of the Order is corrupt, and seeks to extend its control beyond the borders of the Kingdom.
Within the Free City of Greyhawk itself though, it has recently become fashionable for magi to ally themselves with a House of the Order. It is neither required, nor are members of the Order in the majority, but it is beginning to grow in influence. Unlike the 'real' Order in Aerdy however, the Order in Greyhawk is not corrupted by the Infernal.
There are two major differences between the World of Greyhawk and Mythic Europe, and both have been reconciled with a single bound. The first, and most obvious, is the presence of humanoid and demi-human races in Greyhawk, many of which were commonly used as player character races in that game.
Meanwhile, back over in Mythic Europe, the powers of faerie is ever present, and very much grounded in real European folklore.
What I've proposed, is that all of the non-human races within Greyhawk are descended from the Fey. The powers of the Fey though are much reduced, and much rarer. The combined act of the Invoked Devastation and the Rain of Colourless Fire sealed many of the paths between the mortal realm and the realms of Arcadia. Those faerie residing on Oerth at the time of the Closure, became trapped, unable to return to their natural homelands, and also cut off from the source of their powers.
To varying extents, the remaining faeries become mortal. Unseelie faeries were greatly affected, with the goblinoid races loosing many of their faerie abilities.
The elves were the least affected of the demi-human races, though even within this race there are variances. Wood Elves are still close to their original heritage, while the High Elves, who spend much of their time in contact with humans, have lost the most.
The shift from faerie to mortal has been a gradual one, and it is still continuing. Eventually, unless the paths to Arcadia are once again reopened, the descendants of the Fey from before the Closure will have lost all of their faerie heritage.
Demons are another important facet of Mythic Europe which is treated somewhat differently with the World of Greyhawk. The planar arrangement of the multiverse has been kept from the Greyhawk setting, though exactly how it all works depends on the viewpoint of each religion. Generally, demons, devils and other evil powers have been lumped together under the general category of demons.
On the whole, demons are somewhat more intelligent, deceptive and behind the scenes than they are often portrayed in Greyhawk. Of course, the Kingdom of Aerdy and the Lands of Iuz are crawling with the blighters. Such regions will have very high Infernal Auras, with even generally tame regions having auras of one or two.
A complicated issue, since there is not a single, all powerful God amongst the pantheons of Oerik. Any person who has true faith, has it in respect to a single god. Occurrence of True Faith is somewhat more common within Greyhawk compared to Mythic Europe, though it is still reasonably rare.
Some gods in the land of Greyhawk are really little more than demons, and Ars Magica treats the worship of demons quite differently from the worship of gods. For purposes of simplicity, such gods are treated as demons, so their worshippers will not have True Faith.
Iuz for example is a demon, and any priests of Iuz will have goetic powers rather than miraculous ones.