One element to note for a campaign in Iorth are the main sources of conflict in the setting. These conflicts are the main means through which adventurers can try to strive in the world and achieve great heroics and renown.

The Spiteful Serpentfolk

The humanlike serpentkin and more monstrous serpentfolk (a.k.a. yuan-ti & medusas) are a major force of Evil in the world of Iorth. Fanatical believers of the cruel ways of the Path of Darkness and in zealous devotion to the serpentine great old one Glykon, they represent one of the major sources of conflict within the world of Iorth. The key strategy of the serpentfolk is infiltration by serpentkin and corruption from within. In many instances, the serpentfolk strive to have their enemies—essentially anyone who isn’t one of them—destroy each other and weaken themselves to the point to allow for the serpentfolk to easily overwhelm and eradicate them. This ambition is a global one, and thus scheme against mortal, giant, dragon, celestial, and fiend alike.

Using current D&D resources, monsters such as medusas, salamanders, and yuan-ti are ideal to use as members of the serpentfolk. Hydras are often used by the serpentfolk in various capacities. Spirit nagas and marilith demons are ideal fiendish allies and patrons to the serpentfolk, as well as any serpentine great old ones.

The Path of Darkness

The cruel beliefs and philosophies of the Path of Darkness present a formidable threat to the peace and safety of everyone in Iorth. Though united in belief, the extreme selfishness promoted by the Path of Darkness inevitably leads to schisms and factionalism within their ranks. In many cases, many sects of believers bind themselves in dark devotion to a particular fiend, such as an archdevil, demon prince, altraloth, baernaloth, or fiendish empyrean titan.

The only place that openly worships the Path of Darkness is the tyrannical city-state of Hellport. Ruled by the vicious Archduke of Hellport, the city-state serves as the base of operations for multiple malign organizations and endeavors. These forces work openly and in the shadows, all in effort to gain power over everything and everyone else. Various groups within the Path of Darkness scheme alongside the serpentfolk, though both groups plot to overthrow the other once the time is right.

Using current D&D resources, virtually any foe could be associated with a sect or faction within the Path of Darkness. Cultists are some of the most obvious types of foes, but fiends, undead, or any Evil-aligned monster or foe could be serving the grand goals of the Path of Darkness in some direct or indirect form or fashion. A group of bandits could be involved in the plans of the Path of Darkness just as easily as a cult sect, a cruel noble, or even a malicious giant or dragon.

The Hordes of the Horror

The monstrous aberrations of the alien demiplane known as the Horror (a.k.a. the Far Realm) seek to wreak havoc upon the multiverse for reasons known only to them. As such, a few beings have slipped through the numerous barriers that keep their maddening kind at bay, and have taken root within the deep and dark places of Iorth. Though these beings may appear to work at cross purposes to each other, they all abide by some horrid plot meant to undo existence. The creatures and great old ones of the Horror are the rotting remnants of the dreaded cosmic beast that the overdeity Os slew and used to form the whole of reality from. The dread cult of the great old one Yusis but one if their dread number, though the most fearsome known to the wise folk of Iorth.

In the depths of the subterranean realm of the Nether Lands, there are entities from the Horror who set about their foul work. A horrid creature commands masses of twisted deepling devotees in slavish worship to itself. An entity known only as the Overseer commands a malicious network of agents both mortal and aberrant in an obsessive quest for power. The twisted derogar, remnants of experiments of these beings, serve the incestuous outcast dwarves of the Leadfist clan in their captured base of operations in the old cave elf realm of Undor. Cruel twisted beings from the demiplane known as the Chaotic Maelstrom are summoned to the mortal realm to serve as emissaries of the monstrous entities of the Horror among the mortals of Iorth.

Using current D&D resources, aberrations are the main sort of adversary involved in the schemes of the beings from the Horror. The Overseer is a powerful beholder crime lord, with a mind flayer second-in-command. The deeplings (creatures akin to kuo-toa) slavishly worship a powerful being from the Horror; some revere the great old one Yus, while another group reveres an ancient aboleth stranded in Iorth. While slaads are favored agents of some, it is the cruel death slaads that are favored above all by the forces from the Horror. (In fact, there are a few whispered rumors by shunned scholars who delve into the lore of Yus that the great old one is the first and greatest of the death slaads who was elevated to great old one status.)

Other Conflicts

Though not as pervasive as the threats of the serpentfolk, the Path of Darkness, or the beings of the Horror, there are other potential sources of conflict that could require the efforts of heroes to address.

The Prophet of Mammon

One secretive cult that strives to gain power over the whole of Iorth is the followers of the so-called Prophet of Mammon. This being, said to be the progeny of the archdevil Mammon with a night hag, rules a fiefdom in the Hellish Abyss (akin to a portion of a layer of the plane of Gehenna). This fiend serves as a patron to devout cultists and aspirational warlocks, but also has his agents seek to corrupt mortals into his service through the favored vice of his forebear: greed and envy for wealth.

Agents of the Prophet of Mammon may draw on or have fiendish powers or agents, but more often than not they rely on using wealth and the corrupting promise of it to achieve their goals. Evil dragons seeking to expand their hoards are just as likely to succumb to the lure of the Prophet of Mammon just as much as a mortal profit-hungry merchant or a status-seeking noble. Already the works and temptations of the Prophet of Mammon have enthralled generations of the House of Humperdink, a gentlemerchant family based in the city-state of Newton. Key servants of the Prophet of Mammon are marked by their own wealth, but also a piece of jewelry set with a fuchsia gemstone that emits a faint, unearthly, disconcerting glow in dim light or darkness. It is said these gems are offcuts from the original gem fit into the golden ring worn by the Prophet of Mammon himself.

The War of Fire and Frost

Over decades, there has been a secretive war for dominance unfolding between two elemental entities through their proxies on Iorth. The vestiges of paraelemental entities have infused themselves in some of the last of the true giants of Iorth. A paraelemental ice entity took refuge within a mighty frost giant lord, while a paraelemental magma entity rooted itself within a powerful fire giant noble. The frost giant lord and fire giant noble have continue the timeless war of their paraelemental masters, and use their mortal servants to achieve these goals. They would see the whole of Iorth destroyed by their preferred means of annihilation.

Fire and ice are the primary themes for these foes, and any number of monsters and servants could be enlisted in the ongoing clash of the War of Fire and Frost. Confronting the masterminds of this conflict should be an epic event, with the heroes facing off against one or both of the empowered giants at the heart of the conflict. (At the minimum, a frost giant ice shaper and a fire giant forgecaller could serve as the titular masterminds, but the more ambitious or epic campaigns may have a scion of Thrym and a scion of Surtur serve those roles.)