The Frozen Ruins

Ancient ruins in the furthest northeast corner of Emaul. The Frozen Ruins were once the home of a powerful contingent of mages and sorecerers, separating themselves from the rest of the word to further their understanding of magic and the gods. About a thousand years ago, however, witnesses saw a massive shockwave of dark, necrotic energy erupt from the fortified settlement, expanding for miles before it dissapated.
Initial search parties attempting to reach the region reported feelings of unease as they approached, with growing nausea, dizziness, and paranoia in even the most hardened warriors and adventurers the closer they got. Before any reached the walls, the groups were always forced to retreat. Early explorers and adventurers in those conquests routinely fell violently ill in the months following the attempts, reporting yellowed skin, loss of teeth and hair, extreme confusion and disorientation, and vomiting blood.
Generally believed to be under the influence of a very powerful curse, the ruins and the forests surrounding them were avoided and warned against. At the time of the explosion, many goblins and bugbears had settled in the surrounding forests, and the following centuries found increasing number of them migrating out of the forests and into the surrounding lands, many with significant effects on their health from the curse. They brought many rumors and stories of trolls, who had lived the closest to the epicenter, becoming monstrocities, with none escaping the curse. To the present day, the largest population of trolls has never been found, believed to be long dead.