For nearly as long as mortals have worshiped the gods, mortals have known hubris and the gods' righteous anger. When a mortal's offense grows too great for divine patience to suffer, the gods lash out through plagues and floods, and through their terrible servants. Of these vengeful minions, the behemoths are among the most feared. A god or coalition of gods creates a behemoth from the wellsprings of primal chaos, binds it into a semblance of flesh, and fills its mind with righteousness and the thirst to destroy all in its path. The beast is then turned loose upon its victims—those deemed most deserving of bearing the brunt of the wrath of the gods. Some deities stay close at hand as their beasts savage the lands, the better to turn the creatures aside once their divine anger is appeased, while others turn their backs on mortal plights, leaving behemoths to expend their anger until naught but lifeless cinders remain. Entire worlds have been destroyed by these living retributions. Such shattered lands might have nothing left alive save for the conquering behemoths themselves, immortal, living monuments to murdered worlds.

While behemoths are created by the gods, their forms and countenances are the result of which of three domains they have been created to rule—air, earth, or sea. Each of these realms is in turn associated with one of three common types of behemoths—if the application of a word like “common” is even appropriate for such an uncommon creature.

Behemoths cast upon a world's landmasses are known as thunder behemoths. These are the least of their kind, yet they are formidable, nigh unstoppable engines of armageddon nevertheless. They are the behemoths of choice when it comes to destroying a single nation or empire, for while devastating, they are bound to the land itself, and their advances across a globe are thus more limited than those of the two greater behemoths.

When several nations or regions evoke the gods' wrath, a thalassic behemoth is sent into that world's oceans to wreak havoc. By disrupting oceanic trade, destroying port cities, and rendering well-populated shores all but uninhabitable, thalassic behemoths excel at destroying civilizations where they are most vulnerable. A vengeful god may inflict several thunder behemoths upon a realm that has wronged it, placing a thalassic behemoth in the ocean to finalize the devastation.

The most devastating of the three common behemoths is the tempest behemoth, a tremendous birdlike monster capable of devastating numerous lands in a short amount of time. Because it rules the skies above those lands the gods wish to smite, the tempest behemoth has greater mobility than its other kin. When the gods are truly vexed, they might set upon a world numerous behemoths, but the conditions that might call for the deployment of more than a solitary tempest behemoth boggle the mind nearly as much as the sheer size of any of these monsters does—few worlds are capable of the level of blasphemy and hubris that would necessitate multiple tempest behemoths as divine punishment.

Other behemoths exist, such as sirocco behemoths that flay with air and fire, behemoths of the lightless depths of the oceans, and dread holocaust behemoths forged of lightning and fire. Some deities take particular delight in spawning truly unique and powerful behemoths—many scholars place the legendary tarrasque in this category, even though its powers are quite different than those shared by most other behemoths. Regardless of their nature, each behemoth suffers a single flaw by which it might be slain, a chink in its immortality. Some attribute this weakness, however small, to the imperfect process of binding chaos to order, others to divine caution, lest a behemoth one day prove a match for the gods themselves.

A behemoth's creation is not always the act of a cruel god seeking to inflict devastation on an innocent world—often, these monsters are created by good or neutral deities to serve as instruments of justice. Perhaps ironically, gods of a more lawful or civilized bent are the most apt to call up a behemoth, as gods of the natural world either aren't inclined to punish mortals at all, or would instead make use of natural disasters like earthquakes and storms to teach lessons to their wayward followers. While a single behemoth usually suffices, multiple creatures of this kind are sometimes visited upon a world. While it may be small solace, behemoths are incapable of procreation—regardless of the total number of behemoths active on a world at any one time, that number does not increase without the direct, vengeful intervention of a deity.

Even societies that refrain from insulting the gods are not immune to the behemoth's wrath, for the gods rarely remove these beasts when their work is done. An ancient civilization destroyed by a behemoth may still harbor in its ruined heart a slumbering monster, waiting only for the right moment or a tragic accident to waken and ravage once again.