From what I've heard, it's a pretty cool place
A sea of urine where rats eat your face
A sadist like me can pursue his vocation
I'm going to hell because I need a vacation
Gwar, Go To Hell!
A realm of legend and folklore where Elves come from, a source of magic, living fire, and deep torment. It is not common to be certain whether or not it exists, but sorcerers and mystics have confirmed it - often to their great misfortune. Parents from every corner of the continent tell stories about its demons to frighten children.
Of course, Demonic is simply a name we give to the Spirits who stand in opposition to the solar doctrine of Karna. Profundum is not their realm - it is more likely a sovereign realm of pure chaos and magic. Historically, since no other continents have been found on Karnum, any empire that seeks to expand its lands beyond the known attempts an incursion into Profundum at some point, and inevitably causes its own downfall by annoying multiple Elves.
The doctrine among Cult of Karna scribes is that Profundum is where souls coalesce as mystic pabulum for the deity. Good or bad, all souls become the food of the gods. Cult of Speed academics hold that Profundum is a battleground where Demonic forces battle with the souls of dead heroes in an eternal struggle for cosmic supremacy, and the living witchfires of this hell-realm are but the shades of corrupted souls consumed by madness, or some rot of the soul. In contrast to the Human theologies, heretical Canidaur doctrine has it that the sun in the sky is not even the solar deity at all. They suppose we are all living within the mind of Karna, and the sun is merely the window of His eye gazing watchfully into Profundum, whose light is reflected by the moon. They take this as an explanation for The Demon Moon, and for why it hurts to look directly at the sun.