Leaving aside what Nazel and her party encountered after boarding Ocasuan, let us turn our attention back to the Abyss.
The Plain of Infinite Portals was the uppermost of the Abyss's countless layers. It was a barren land, devoid of life or vegetation, buried beneath thick dust and scorched by a hellish crimson sun. Three types of terrain dotted the dusty plain: massive fissures in the ground, enormous iron fortresses, and the Styx.
The fissures on this uppermost layer led to deeper levels. By descending through certain specific chasms, travelers could quickly reach the corresponding layers, though jumping carelessly into a fissure leading to an unfamiliar plane of the Abyss was an extremely dangerous act. Most fissures were two-way passages, but some were one-way only, abandoning travelers who became trapped on a new layer.
The iron fortresses here were usually inhabited by powerful demons and their minions. These strongholds often served as assembly points for demon legions marching toward the endless Blood War. Some of the largest battles of that war took place on this layer, in the deeper layers, and in the nearby Outer Planes. The Styx wound its way through this layer. Some channels plunged into the Abyss, while other chasms spewed filth, becoming tributaries of the Styx's main current.
By comparison, traveling on the Styx was relatively safe. At least the Styx Ferrymen had no flaw beyond charging exorbitant prices. Normally, these ferrymen were the very definition of evil, and robbing fellow criminals was commonplace for them. But as long as you were on their boats, they would strictly follow the rules. What happened after you reached your destination, however, was another matter.
Long ago, the Plain of Infinite Portals had served as the Abyss's springboard for invading other planes, because it contained many spatial rifts leading