Abyss

The Abyss is home to demons, several of which has found their way into the Land of the Mists, whether by being summoned or via transposition. The Abyss can be joined to the Land of Mists via a portal in the form of an artifact called the Key to the Abyss. The knowledge of the existence of the Abyss is obscure knowledge in the Land of Mists.

References

Carnival, p. 46.