This abyss has the design of a forest and a theater.
The portal is located in the area where you killed Oberon Greenhaze. Here, the elves who died went to an abyss where they had to watch and participate in a badly performed play about their defeat at the hands of the dwarves.
The elf Oberon Greenhaze is punished to watch this play from the first row, trapped in a tree in this abyss. The play called the "Terror of Evernight" repeats the first two acts again and again, since the "terror" for the concluding third act is broken (not working).
Then the Overlord comes in and discovers the "terror" Goldo's steamroller Rollie as it turns out and also locates the missing pieces for it, so that the play can finally come to an end. The Overlord navigates Rollie, running over the stage elves, to finally burn Oberon to ash, revealing the abyss stone trapped behind the hero.
After the play ends, the Overlord attempts to steal the abyss stone, but the elves revolt and try to destroy the stone, only to be defeated by the Overlord.
Upon revisiting this abyss, depressed elves can be seen burning down the decorations on the stage.