Hexes 0508, 0509, 0608-0613, 0707-0713, 0807-0813, 0908-0913, 1007-1014, 1109-1114, 1210-1215, 1312-1314 and 1413 on the Cauldron and Hinterlands map.
The Wastes are an old battleground that was devastated four hundred years ago. The area used to be the southern border of the Kingdom of High Kaddish until a cannibal immortalism cult known as "the Joyous" established itself, killed most of the inhabitants and were preparing to sacrifice the rest to an arch-devil who they believed would lead them to conquer Kaddish. The Undying Strategists authorised the use of the Chains of Life and Death, one of their weapons of mass destruction. The Chains (which resemble extremely fine spiderwebs) link all living things within their radius together so that the death of one means the death of all. Within seconds of deployment, the death of a single bacterium caused everything to die - plants, animals, cultists, victims, and the half-emerged arch-devil. The Chains have mostly dispersed harmlessly by this point, though a few patches here and there can be found. They are still potent (though safe if not directly handled), and the Undying Strategists will hunt down those who fail to return them.
0910 contains the slumped, rotting, upper body of the arch-devil. The area is marked by triliths engraved with runes that glow green under a full moon. The upper body is about 15m long, laying "face" down. It appears as a four-armed mass of deep blue flesh with a bony epidermis covered in projecting horns, ridges, etc. The bones are extremely valuable to gnostics, collectors and smiths. The creature completely fills the portal, which is still open. Over the intervening centuries, lesser devils have been gnawing their way through his lower half, attempting to escape into the world. Cutting the arch-devil apart for its bone will free them.
Only one member of the Joyous survived the attack. He is an gnoll who calls himself "Eater-of-Corpses" who has lived these past four hundred years preying on travellers. He avoids consuming their pineal glands, which mean his victims rise as undead, which he binds to his service. Eater-of-Corpses has a small hut in 1013 which he is based out of, though he roams the plains.
The people killed in the attack have congregated for unknown reasons in 0709 as undead. There are about a thousand of them still active enough to be a threat, and they are clustered around a grey stone statue of a leopard that the ancient Hazilua carved, though no one knows why.