Hellfire CR 3
The iconic flames of Hell take many forms, but typically burn with either crimson or sickly green flames, sulfuric and flaring on any terrain or substance and needing no fuel. Hellfire’s damage is half fire damage and half damage from unholy energy; evil-aligned creatures and creatures with the evil subtype take no damage from the unholy energy, but good-aligned beings and those with the good subtype take double the normal damage from it. Creatures under the effects of spells such as protection from evil are unaffected by this unholy energy, though they are still subject to the fire damage.
At times, sheets of hellfire rain down upon the surface of Hell. Raining hellfire functions as precipitation, but also inflicts 1d6 points of hellfire damage per round. Hellfire rain doesn’t harm objects native to Hell, but flammable objects that are left unattended can quickly be consumed by hellfire rain. An instance of hellfire rain typically lasts for 3d6 rounds, but in some cases can last much longer.
A typical gout of hellfire typically deals 6d6 points of hellfire damage. Aside from such gouts, whole lakes, burning clouds, pyroclastic flows, burning rock, and endlessly smoldering structures flickering with hellfire are known to burn amid the depths of the Pit.
Pathfinder Chronicles: Princes of Darkness, Book of the Damned, Vol. I. Copyright 2009, Paizo Publishing, LLC; Author: F. Wesley Schneider.