During the great war against the elves, many potent magics were unleashed, including a massive Stone to Flesh spell that transformed an entire chasm in the badlands into a living mass of flesh, teeth, eyes and mouths. The chasm exists well outside of civilization, supposedly in the badlands to the East, near the desert of the gods. No one knows if the chasm was sentient from that point onwards, or perhaps that it was sentient even before being converted from stone to flesh; but today it is a vicious and unpleasant sage and source of strange knowledge for those who are willing to deal with it and trust it to keep it’s side of the bargain (and not eat the petitioner in the process).
Further, there are those that have learned to tap the mighty life force and ancient knowledge of the chasm (most with, but some without it’s willing permission).
It is said that the Living Chasm is one of the original teachers of the craft of flesh, and that those who learn it’s potent magics typically become Fleshcrafters (and others have been said to learn spells from the fleshcrafter spell lists, permanently replacing regular magic user spells from their spell lists).