Great isolated swamps steeped in magic. The spawn of demons of filth and ruin trapped in watery prisons. Where the Planes of Earth and Water meet. Wherever there is mud and magic and time enough, you might find a mudlord. While their origins vary, their attitudes don’t—they hate the intrusion of humanoids, and will drive them out at every opportunity. Exceptions to this rule are singular individuals indeed…and still not to be trusted lightly.
The demon Orvigal’s prison was designed to quench the fire of his vile spirit, chaining him spread-eagled in an aqueduct channeling a constantly flowing freshwater stream. All went well until a dam was built downstream, giving the putrid runoff of his essence time to fester and coalesce. Now a gang of fiendish mudlords has made its way back upstream to the library that hides Orvigal’s prison. Warded from entering the aqueduct itself, they work to sink the structure into the mire so they may free their vile father.
A mudlord has fallen in love with the dwarf enchantress Verine. His steadfast support has allowed her to journey widely without fear. During encounters, the mudlord Ix typically hides in mud puddle form, then rises up to attack if a situation arises that Verine’s natural and magical charms can’t handle. At times Verine will even wear Ix at a suit of mud armor, protecting herself from blows so she has more time to get her spells off before Ix leaps off her and attacks.
Half-elven conquistadors from San Tropau have been warring with the ifrit tribesfolk of the Rainbow Dragon Nation, pitting halberds, crossbow bolts, and clerical might against tomahawks, shark tooth-tipped arrows, and fire magic. Adventurers might find themselves drawn into the conflict on either side or as go-betweens, particularly as both factions are desperate for spell components and medicine to ward off swamp sickness. But when the fighting draws the wrath of a hidden kingdom of mudlords, all that matters is survival, as the xenophobic mudlords send allosauruses and earth elementals to smash every humanoid flat.
—Pathfinder Bestiary 4 195
I seem to remember early editions of the world’s oldest role-playing game featured the mudman. But with Internet being 55¢ a minute on this boat, that’s a Google search I’ll save for another day.
I also seem to remember a really great Where’s Waldo book…the third one maybe?...that explored fantastic locations. And one of them featured dryads vs. mudmen or dryads and mudmen vs. someone else (knights maybe?). Whatever. It was an awesome spread.