The Inferno

The Firelands, Hell, the Abyss - all these names refer to the Inferno, home of fiends. Demons and devils frequently escape into the material plane and wreak havoc in their attempts to spread misery and collect souls. Some spells and rituals can open temporary portals to the Inferno to summon these fiends, usually for nefarious purposes. Beyond that, it is unclear how infernal beings make their way into the material realm.
The Inferno consists mainly of six different regions, though spaces between these zones exist as well. The River Styx flows through its fields and valleys.
Fiends slain outside of the Inferno dissolve into ash and reform there. They typically require time to recover before they can return to the material plane again. Fiends killed inside the Inferno are slain permanently, just like a mortal creature. They are much more difficult to kill in hell due to a number of prevalent latent effects:

Spellstrain

All fiends deal double damage

All fiends gain a +3 to AC and spell/feature DCs

Features

• Lucris
• Glacis
• Tristis
• Perodis
• Tenebris
• Putris
• River Styx