Felhunters (also known as Felbeasts, Felhounds Felstalkers, and the hounds of Hakkar) are magic eaters that feed on arcane energy, an energy that fel energy is counteracted by. The volatile arcane energies—the lifeblood of a nascent titan— are the energies of the Twisting Nether, an astral dimension separate from the physical universe, and so these hunters presumably reside in the Twisting Nether, searching for arcane energy to feast upon, or travel in-between the Twisting Nether and the physical universe.
As demons, felhunters were formed as a result of Light and Void energies that bled together at the borders of the Twisting Nether. Many of these aberrations indulged in the highly volatile energy that pervaded the Nether and, before long, these bloodthisty demons clawed their way into the physical universe, terrorizing mortal civilizations and bringing ruin to world after world.
Professions of the Cosmos
In the face of demonic power (or warlock magics), most heroes see death. Warlocks see only opportunity. Dominance is their aim, and they have found a path to it in the dark arts, the arts of necromancy. These voracious spellcasters summon demonic minions to fight beside them. At first, they command only the service of imps, but as a warlock’s knowledge grows, seductive succubi, loyal voidwalkers, and horrific felhunters join the dark sorcerer’s ranks to wreak havoc on anyone who stands in their master’s way.
They can sense the presence of nearby magic and hunt spellcasters unerringly. It looks vaguely like a hound — though one with a massive, toothy head that makes up nearly a third of its length. Great horns jut out above its solid white eyes. Their powerful jaws are huge and filled with slender teeth. Their eyes are weak; to get around, they rely on their ability to sense magic. This sense is also how they track their prey. They are pit lords' personal hunting hounds, starved for both blood and arcane energy. Pit lords grow them somewhere in the Twisting Nether. They do not speak, though they understand Eredun. They treat spellcasters, particularly arcane spellcasters, as layered desserts with meat on the outside and magic on the inside. Less magical characters are worth notice only if they have damaged a felhound.