Great Blight

From Wotpedia

The Great Blight is located north of the Borderlands. It is the place in the world where the Bore in the Dark One's prison is closest to. Inside the Blight are the Mountains of Dhoom, Thakan'dar, Shayol Ghul, and the ruins of Malkier. Everything in this region can cause painful death, even plants and small insects. The Great Blight was created when the Bore in the Dark One's prison was created and he destroyed the city around which it was drilled. The Blight is populated by Trollocs, Myrddraal, Worms, Draghkar, and other forms of Shadowspawn. The sole purpose of the Borderlands is to guard the world against the Shadowspawn that live in the Blight. Deep in the Blight is Shayol Ghul, and inside Shayol Ghul is the Pit of Dhoom. The Pit of Dhoom is the closest you can get to the Dark One. Here the Dark One can twist reality, and even speak to you directly. The Pit of Dhoom will likely be the site of the final battle between Rand and the Dark One.