Greetings!
Indeed!
Hey there Sword Dancer!
Well, as to "High Magic" campaigns, much of the previous advice and commentary are quite excellent.
As to some ideas about running High Magic campaigns, there are some thoughts in good order;
In a different thread about "High Magic" campaigning, my friend Dragonblade discussed at length the strange dichotomy within the rules of having virtually all npc's being thought of as 1st-3rd level, as per the DMG's assumptions, while having a different set of assumptions for the player characters, as in they are of course high-level, and have access to magic on a routine basis, and do not fall under the same set of assumptions and restrictions that the standard npc's do.
First of all, this typical campaign assumption, if embraced, brings with it a series of problems and disrupts consistency in a later blossoming "High Magic" campaign.
Unless you want the player characters to run roughshod over nearly every environment that they encounter, this needs to be thrown out the window. To my mind, limiting npc's to such low levels doesn't mesh with reality. I find it difficult to believe that reasonably experienced and skilled adults are usually no higher than 3rd or 4th level. In any event, this kind of thinking is typically a holdover from previous 1st and 2nd edition philosophy, and should be discarded.
Once you as the DM are free of these kinds of assumptions, you are then free to change the assumptions to most adult npc's being in the range of 5th-12th level. This dimension then further extrapolates into there being more characters of whatever class of higher levels, say in the range of 12-30. This then allows for more characters of above 20th level not being quite so rare or extraordinary.
This assumption then makes it more reasonable and easy to design and accomodate challenges for characters above 15th or 20th level. This, of course, makes for a more balanced, logical, and challenging game experience at higher levels.
By the way, this doesn't mean that player characters are no longer special, or that it means that epic level characters are *necessarily* "common". Rather, it simply changes their frequency and logic of occurrence to a higher degree than what is the default assumption. Exactly *what* degree of occurrence, being somewhat more, a lot more, or quite common, for example, is easily left up to you the DM, and easily controlled and extrapolated.
That set of assumptions determined, then, allows one to look to other matters and details.
For example, it isn't really consistent to try and *force* a typical medieval European 12th century environment, in light of the magic that is, according to the base assumptions of the rules, readily available.
Again, for example, the access to even moderately powerful spells of under 5th level would dramatically change any kind of campaign environment beyond recognition to that of a typical 12th century European model that is so often the favourite of many.
Think about the effects of 3rd level Cleric, Druid, and Wizard spells to the fabric of an entire society. The implications are staggering! The effects on the health, livelihood, and happiness of virtually the whole population would be huge. Imagine the effects of a powerful, wealthy, nation-state that would see the effects of magic on the whole society? It isn't unreasonable to assume that powerful kings would finance and support the establishment of powerful churches and wizard guilds so as to increase the training and recruitment of talented and skilled clerics, druids, and wizards. The safety, security, and continued success of the kingdom at large would be at stake, and no monarch would doubt the power and efficiency of magic to affect the kingdom on a constant level.
Essentially, after a few kings put lots of money, support, and energy into it, entire populations would have a broad access and superior health, skill, and efficiency across the board from economics, to agriculture, to engineering, to warfare. Tribes and kingdoms that failed to do so, for whatever reasons, would soon fall way behind and be trapped into a sort of hopleless backwardness and inefficiency that would make them decidedly primitive by comparison to the wealthy, advanced, united, and powerful kingdoms that embraced magic throughout society.
Have you ever thought it strange that throughout many campaigns, the cultural achievement index is always static? What I mean is, why is it after say hundreds, or even thousands of years, a given society is still locked into the 12th century medieval European paradigm? Just imagine what one generation under one energetic king focusing on integrating magic into all levels of society would be like, then imagine the progress that would be made in not only that particular kingdom, but also surrounding kingdoms, year after year. Imagine the advancement after a few hundred or a few thousand years, and it becomes readily apparent that the whole fabric of society would be very, very different.
These reasonable and logical assumptions would then coalesce into magic being integrated throughout all levels of society, where food is plentiful, healing is extensive, and the base population has long, vibrant, productive lives. People would be vastly more efficient with magic to assist them in production, labour, and economics in a myriad of ways.
In consideration of your meliue, these kinds of factors can create a vibrant, unusual world!
As to some philosophy, embrace the high magic of the rules; embrace a logical ecology of creatures, and run with it! Instead of trying to restrict, restrict, restrict,--embrace it with a passion! See where that takes your campaign! Don't be content to merely let the player characters be the movers and shakers and innovators, but have fun yourself! Allowing other npc's for example, to become famous wizards and innovators in society won't necessarily "outshine" the player characters, but instead serve to inspire them with the grandness, the richness, and the fantastic diversity of your campaign world!
Remember--the game is for fun, but also a game of the imagination! Let your imagination run wild! Look at, and *use* the various supplements available! Get into them, many of them, and make them go to work in your campaign meliue! Following these guidelines with some care, and putting some effort not only into the "thoughts behind the machine" but also into integrating them into your campaign world will guarantee an unforgettable campaign experience!
Semper Fidelis,
SHARK
