Terrestrial
Mundane fire that burns away physical matter and is present in all realms, but the only kind found naturally on Earth. Heat levels are based on flame color ranging from red(coolest) to white(hottest). As a natural element it reacts negatively with its counter element—water—and is the only type of fire to do so.
Hellfire
Infernal balefire* that burns not only physical matter, but souls and spirits. Regardless of its strength, hellfire is always green, although white and black can be present at times as it interacts with objects. The flames smell of pungent sulfur no matter what they are burning.
Hellfire affects physical matter the same way as terrestrial fire and it also harms spirits in a similar manner. Depending on its strength, hellfire at its weakest will corrupt souls which saps them of their strength and causes a variety of ill effects to the host such as extreme fatigue, weakness, confusion, and nightmares. Supernatural beings can experience a significant loss in their powers. Weak willed individuals will go through a rapid moral decline as the brand of Hell drives them toward madness and evil.
The most powerful hellfire is one of the few forces in any known universe capable of outright destroying souls, denying them from the cosmic cycle and effectively erasing a person from existence so that they may never be reborn.
As with most otherworldly fire, water does nothing to extinguish it, nor does lack of oxygen. Hellfire does not always have to be hot either. While mundane fire is based off increased energy exciting particles to trigger combustion, hellfire is mystic in nature and can cause the opposite effect if desired to induce frostbite and freezing.
*Balefire is a term to describe any mystic flame used for insidious purposes.
Underworld
These dark flames are unique in that they are not a separate element of their own. All “dark” elements originating from the Underworld are a manifestation of death energy and an aspect of Death itself. Unlike other fires that are simple and common to their native realms, conjuring dark elements takes enormous skill and a pact with the essence of Death often at the cost of the caster’s mortal shell.
Underworld flames at their weakest are a bluish purple and pitch black at their strongest. They affect physical matter and even other forms of energy not by burning, but enfeebling, decaying, decomposing, and withering as all dark elements do. These flames can also be used to manipulate inanimate objects as a liaison for Death. A marked machine could be made to malfunction and wait to kill the next user or set off a chain of events that would indirectly lead to their downfall.
Souls struck by Underworld fires feel the same debilitating weakness as when hit by hellfire. Spirits take direct damage, but that done to souls is actually an attack on the tether binding the soul to the body. Death does not partake in the destruction of souls, as its main function is to keep balance between the living and dead and without souls there would be neither. As the soul is severed from the body it may feel that the flames are burning cold to the victim, however to others nearby they remain the same.
Celestial
Also known as holy fire or heavenly fire, it is the only flame that radiates supernatural light and burns pure white no matter the strength behind it. Not much else is known except that it has no effect on the soul unless corrupted and interacts with hellfire as water does terrestrial fire.
Fae
Fae or wyrd fire is an artificial flame hailing from the lands of Arcadia—a “Counter-Earth” that exists in a parallel dimension. This fire sparkles and burns with a pale prismatic flame that radiates no heat. The inhabitants of Arcadia are known to be more closely in tune with nature than their counterparts on Earth, so they devised an alternative to mundane fire that could still be used in combat without the threat of spreading across the wilderness.
Fae fire is a manifestation of aether and as such has the most impact against spirits, but also the mind of sentient creatures. It was first conjured by ancient Arcadian mages after generations of research into a flame that would not harm physical matter nor the soul, and has since become a staple in their battles. The flames erode the conscious mind, inducing a malaise of bewilderment and making it more susceptible to illusions, but leaves the body unscathed.
Stronger flames send acute pain throughout the nervous system making the victim panic and feel as if all nerve endings were doused with molten steel. They are often flooded with “scent memories” as the flames burn away their inner thoughts. At its worst, Fae fire can shatter the conscious and subconscious causing a total lobotomy to living things and preventing spirits from manifesting, at least for a time.
Being that Fae fire is aetheric in origin it can interact strangely with other arcane items, such as by being imprinted onto weapons.
Wyrm
Greater draconic beasts native to Arcadia breathe a hybrid of terrestrial and mystic fire that is immune to water. This fire is always within the yellow-red spectrum, however it burns at white-hot temperatures to start. Being a form of mundane fire and igniting by combustion, wyrm fire is based on the principles of heat. Although this fire can burn underwater, it is negatively affected by cold temperatures that rapidly slow the movement of energy between molecules from its breath and can be extinguished or even frozen as a solid.