In the area directly behind the gate, Eisen could immediately see that this fight would end up being completely different to the fight that he just fought in the other 'arena'. He was surrounded by trees immediately. But not the natural, pretty kind that would make this place seem like any normal forest.
Rather, they were dead, hollow trees with thick mist flowing inbetween them, making this place feel creepy and eerie.
The first ring of the circle of violence was for those that inflicted harm upon others, so he had to fight something that was practically addicted to murder. This second ring, however, was for those that inflicted harm upon themselves, and they were forced to live in this forest of suicide.