I've got a long-term, general DnD homebrew project I've been working on for funsies for a few years now. Not sure if I'll ever end up playing it with folks, I'm just having fun making it!
The 'Big Bad' of this plot and setting is a Wizard Lich, Gregoire. Gregoire has been living in this setting, the Island Continent of Iona (a.k.a. Greyhawk's Australia,) for nearly 5 centuries now. His presence has had such influence as to actively create ecosystems, rewrite the destinies of whole cultures, even permanently change the weather; for example, there exists a volcano sat upon the dense meeting point of several dozen leylines, and thus will occasionally spew raw Arcane energy into the atmosphere. Gregoire triggered the volcano's eruption from the earth on purpose, as a magical equivalent of his own personal nuclear generator.
In its modern abandoned state, the surrounding terrain is known as "The Roils", because the occasional thaumoclastic tsunamis of arcane energy sweeping across the land will drastically warp the landscape each time. It's unmappable, and the only thing more dangerous than its terrain are the things that have managed to survive and adapt to this way of life.
As you can imagine by now, Gregoire had and HAS a very deep and vested interest in Magic. Not in the study of spells, not how to USE Magic. If the average wizard is a weaver, Gregoire aims to learn how the fibers the thread is spun from are made. And it is from this knowledge that much of the 'How The Fuck Did He Do That' which drives the plot comes from.
Which means I had to sit my ass down and figure out, How The Fuck DID He Do That?
So, here's what I've got:
The very first step taken in learning was Magic is, was learning that atoms aren't.
'Atom', of course, isn't a word you would ever hear on Mundus unless you're a well-educated practitioner in the niche field of Mundane Alchemy. Or, in Gregoire's case, unless you are several-hundred years old and were present for the proposition and subsequent debunking of Atomic Theory. This version of Atomic Theory was proposed and built upon much in the same way ours was: macro-observations, pattern-detection, and prediction.
As much excitement as was had over it back in the day, once it was figured out how to peer that deeply into the canvas of the universe… nothing was there. Literally nothing. As it turns out, when you zoom into matter far enough, 'matter' stops being a thing that exists at all.
This was the discovery of what was initially considered the edge of all reality, which Gregoire would later name The Barrier. The mistake they made in defining the Barrier as the 'edge of reality' was assuming that 'not real' meant 'non-existent'. They assumed that nothing was on the other side, making it an edge. In truth, Nothing was on the other side, making it a Barrier.
See, in the same way a statue is carved out of marble and is thus defined by what is removed, Reality exists as a bubble, a bubble of Is-ness defined by the surrounding ocean of Isn't-ness. Gregoire's ultimate discovery was thus: Magic, ALL magic, is simply a manipulation of that Barrier between! He would go on to learn:
Arcane magic is subtractive. It is a precise, local thinning of the Barrier using bits and pieces of Reality to get it to react; words, movements, materials. The same way one plugs numbers into an equation to get an expected result. This allows the magician (or enchantment,) to carefully funnel their chosen Isn't-ness into Reality, making it so. This is part of the reason that the wild potential of Arcane magics is rarely actually reached; breaching The Barrier that keeps your Universe intact isn't a particularly safe practice. Theoretically, given infinite time and infinite chances, a mortal could surpass any known God in terms of Reality-manipulation. Alas, time and chances are in notoriously short supply for mortals.
As mentioned, the thinning-of-the-barrier that is Arcane magic is extraordinarily difficult to achieve at all, let alone safely. The pressure of Isn't-ness is what holds all the Is-ness together, so any hole in that barrier is going to unleash a firehose of Isn't-ness; Is-ness never escapes the other way. So when any reliable method of not-existentially-flashbanging-yourself-and-your-immediate-surroundings is figured out, it tends to stick. There's forty ways to cast fireball but you're only ever taught the one for a DAMN good reason. That 'damn good reason' can be illustrated in the existence of Wild Magic users. For whatever reason, their skills sometimes leave The Barrier open just a microsecond too long, letting in some raw Isn't-ness that'll just occupy whatever empty space it sees fit to Be!
(Gregoire is very fascinated with the high-pressure / low-pressure system the Barrier sits between. He has, in fact, determined that the larger the puncture in the Barrier, the heavier the Isn't-ness flow, and the heavier the flow, the longer it takes the Barrier to snap back shut over it. Theoretically, there is a limit to how strong this flow can be before the Barrier stops being capable of snapping back. Food for thought.)
Divine magic, on the other hand, is additive. It thickens the barrier, reinforcing and rebuilding extant Is-ness, protecting its status from being replaced by something that formerly Wasn't. Generally speaking, what mortals consider Gods are sort of self-appointed hall monitors of the Barrier. No mortal is individually capable of building up the Barrier, only breaking it down. Thus, additive magic — Divine magic — MUST be channeled from a God, not Reality or Self.
While one might assume that Gods occasionally puncture the Barrier to act — Arcane magic — the truth is that Gods are powerful enough to build Reality atop the merest dust mote of concept, so long as it exists within the Is-ness. A God can make a tree where there was no tree before, by layering the existing ideas of 'tree' and 'this location', thickening the Barrier into a lens which reflects this new reality of There Is A Tree Here Now. Gods are the purest expression of Is-ness; Gods MAGNIFY reality, they cannot BREAK it.
Now, if something from ANOTHER bubble of Is-ness — an Outer Plane — was somehow strong and capable enough to fully remove the concept of 'tree' from OUR bubble of Is-ness, no God could make a tree again. No God would remember that 'Tree' even exists, nor could they mourn any of the now-unexistified Gods within the domain of Tree; the biggest collective Achilles' heal the Gods have is that they are MADE of Is-ness. Their extant state is determined by the extant state of what they define themselves by. Being a god of any domain is a very careful balancing act in maintaining that domain without warping it beyond recognition.
This is why Gods tend to be so stiff and single-minded, and why they act through mortals; it's a survival mechanism, and they lack the adaptiveness and flexibility to maintain their domains by themselves in a way that ALSO keeps mortals around to worship them. Any direct interaction a God has with the Is-ness will necessarily be profound in the same way a human touching the surface of water will necessarily shift millions of atoms and send ripples cascading out; this is why Gods do not interact directly with the material world. It's all too likely those tsunami-ripples will hit something that determines THEIR domain. Which is all a fancy way of saying, when a God pokes the Is-ness directly, they usually end up jabbing themself in the eye.
If you got to the end, thankyou for reading!
Source: r/worldbuilding · by /u/CHANN3L-CHAS3R