Abyss

The deepest level of the world, where only Ideal forms exist; what many would call Heaven or Hell. A mortal cannot maintain their ego at this depth. The Idea of Evil resides here, connected through the subconsciousness of the world's inhabitants.

Apostles that die are shown to be dragged into the Abyss by the tormented souls that reside there. Surviving sacrifices, when inside the realm of the God Hand, would also be dragged into the Abyss by said souls. However, those still possessing some amount of life would be able to resist or even shake off the souls rather easily, such as when Guts was able to break free merely through the kickback of his arm cannon.