Niflheim is an extremely difficult endgame zone. It is 3x3 map tiles in size, and 8 of those tiles contain a boss.
You can reach Niflheim by one of the following methods:
- dimension travel to cyan
- entering the one-way staircase at River Gioll, guarded by Harbard
- reading a scroll of pure evil (random chance, strongly discouraged)
The bosses are laid out as follows:
Any bosses not slain will move to Asgard when the player reaches it. They do not need to be slain to win the game, but it's easier to kill them one at a time than potentially dealing with all of them simultaneously.