There is a description of the far realms inside the 5E PHB, or maybe it’s the dungeon Master’s guide. The description follows through for pretty much all descriptive text sections that have to deal with anything Lovecraft related. It goes something like this:
It’s incomprehensible! Your mind literally can’t comprehend it. It’s too alien, too insane, doesn’t abide by the laws of this reality. Your mortal mind can’t handle it.
Boring, isn’t it? It tells you literally nothing about what it is that you’re seeing, experiencing, what the aftershock of such a sight might be.. It’s completely useless. It reminds me of a recent digressions and dragons episode.
You see a creature the likes of which you have never seen before, which is just perfect as descriptions go. Do I know how many limbs it has? Are any of them sharp? “You encounter a creature the likes of which I have not bothered to write down a description.”
I understand the natural inclination to leave something at “your mind can’t comprehend it.” However, as storytellers, we are charged with inventing depictions of the experience, and at this point even ending the story with a simple, fact of the matter “your mind can’t comprehend it” is no longer enough. Sure, we can say constructs of insanity and realms that lie beyond the constraints of our natural laws are beyond our means to explain. Fine! We are not here to artlessly explain how everything functions in a scientific context ( particularly not in the fantasy genre). What we can manage are the aesthetic or linguistic representations of things that lie beyond our full comprehension.
Consider the following:
The light around you is blue, refracted. Something like the surface of the ocean when viewed from beneath lies too the left, then your right, then above you, then moving again. The source of the light is clearly behind it, but looks red despite the soft blue rays it casts.
Or this one:
A gray, tattered landscape lies before you, roiling like a flag, moved by a nonexistent wind. The very horizon shifts in ripples, bending the ground up, up, up until it crests over your head – a quick glance South reveals it to have never moved at all. A quick glance North shows the horizon did indeed crest over you, wrapping ‘round to diminish the sky to a thin line, and the ground 100 miles away lies only a few hundred feet above your head. Looking North again, you can see it never moved at all.
I’m no Lovecraft but, not bad, right? It’s a start, at the very least. Paradoxes are things we characterize as being logically incoherent. Who cares about the explanation? In a moment of madness, the struggle to reconcile the incomprehensible with reality, the description of such an experience is what counts. I be willing to bet there’s a value to doing this inside a game like Dungeons & Dragons. Your players sitting across the table from you, in touch with reality.
Through a clever use of language, I believe we can ever so slightly nudge the player into the shoes of their character as they experience something horrific, or simply inexplicable. They are already engaged in the act of imagination; take advantage of that! Don’t be afraid to invent paradoxes and play with the incomprehensible; with any luck, the group activity this will create a feedback loop as nervous eyes look back to one another in confusion.