Tar’actur is depicted as an endless, jagged plane. There is virtually no significant elevation change, but there are small ravines and hills, just tall enough to be taller than the tallest man. The entire surface is made seemingly of broken glass and obsidian, twisted and sharpened to be the most physically painful thing possible to touch. In addition to this, the temperature fluctuates between colder than any living being has ever experienced and hotter than any living being has ever experienced. When the air is cold, the ground and all physical objects will be at a temperature that is ordinarily hot enough to burn any and all nerve endings away entirely. When the air is hot, the ground will be cold enough to instantly freeze you to it, just like licking a metal pole in a northern winter. You would need to tear half of your skin off to free yourself.
Despite all of this, it is impossible to die. As previously mentioned, the heat and the cold both would normally be enough to completely destroy all the nerve endings in the body, leading to a lack of pain. However, the nerves repair themselves at a rate just minutely slower than they are destroyed, causing one to be in uncontrollable agony for eternity as the nerve endings are very, very slowly burned out or frozen. The pain levels of simply existing in this hell are exponentially higher than anything the living world can even attempt to create. Trying to move around is even more painful, but all the people placed there are also given an uncontrollable urge to travel and move. They are left wandering the frozen and burning hellscape for eternity, never again having any contact with a single other intelligence, living or dead. That is their punishment for their deeds in life.