d66 Monsters of the Necropolis River Delta

You cross over the Dry Red & Ochre Hills and descend to a country of lagoons and channels - feats of ancient engineering swallowed by luxuriant growth and centuries of silt. 

This was where the nameless Necropolis Culture flourished. Swallowed up by the very conditions that allowed it to rise and thrive. 

The seasons are Misty, Flood, Hot, and Rainy - in whatever sequence you like best.

The Tower of the Astromancers is the only remaining intact structure that can be identified at a distance and with any certainty. It's importance to the Necropolis Culture (and those trying to plunder it) may simply be survival bias. But it was definitely somehow significant.

The Grand Necropolis is speculative, but firmly fixed in minds and on maps (though not its specific location).

1. Roll d6:

1. Killer Mud Pigs (1-3): Dire/Prehistoric Capybara, size of a Hippo and equally bad-tempered. Its mud-clogged fur foils infravision, just like in the documentary, Predator (1987).
2. Sentinel Crabs: ubiquitous; about the size of a dog; shells make cheap, short-lived shields. Signal to each other with rhythmic claw clicking, gathering in greater, louder and more intimidating numbers around whatever their current interest. Normally non-aggressive, scavengers and opportunists.
3. Skims: ray-like creatures look like floating mats of weed until they take to the air. Big ones can completely envelop you; small ones are like hairy leeches. Possibly intelligent.
4. Grindylows: Velya to the Croglin Vampire; ghastly clutches of them trapped in shallow pools, whispering for blood and darkness. Coughing cries ring out and are answered during the misty season, as they reminisce and plan for swarming during flood season.
5. Big Sleek Rats: predatory otters. May have ghoulish habits and taint from slithering through the tombs and scavenging the resting undead. 1 on d12 they’re Ghoulish Weres.
6. Banshee Caterpillar (1): named for its distinctive whinnying scream; colonised by bioluminescent animalcules; entrapping web strands; adhesive spit. Eventually burrows into the earth to pupate. No one knows what the adult form is, how long the gestation, nor total numbers waiting to hatch.

2. Roll d6:

1. Greasy Cormorants: nosy, noisy, gluttonous. Will flock your camp to snatch your dinner, and any loose shiny things into the bargain. Defensive and malicious projectile regurgitation and defecation.
2. Giant Catfish (1): can haul/hurl its bulk out of water and over solid ground - survives several hours out of water. Possibly delicious, mostly harmless, can swallow you by accident. 1 on d6 it’s capable of speech and wisdom (or a reskinned Aboleth).
3. Vicious Otters: aggressive and territorial, otherwise common otters. Local lore ascribes them human intelligence and powers of mimicry, if not of actually being shapeshifting witches.
4. Psionic Squid: if you’re immune to their abilities, they are quite sad-looking grey squid. Otherwise appear to be arabesque fractal peacocks with an infinite array of Mandelbrot tentacles. They’re learning to communicate with other lifeforms, but hampered by short lifespan, demanding breeding cycle, lack of transmissible culture. They’re not sure whether to make friends or take over the world.
5. Gross Bitterns: stout, dodo-like swamp birds. Communicate and defend themselves with infrasound. 
6. Lord Verdigris (1): colossal golem, still running on an apparently eternal power source; programmed to ceaselessly patrol the region, but nothing seems to occur that provokes a response. Infrequently dashes off swathes of heliograph messages to the distant Tower of the Astromancers.

3. Roll d6:

1. Terror Crane (1-3): Colossal nomadic wading birds. Incapable of flight. Criss-cross the delta, leaving a trail of incidental destruction and the empty shells of giant marsh clams.
2. Amber Golems: undead-android dinosaur/lizard-folk; guardians and soldiers of the Necropolis Culture, they follow ancient orders but could be reprogrammed. No one living knows the secret of their construction.
3. Thrif (Death Leeches): elemental anemone-urchins that spawn in places with heavy necromantic fetor. Animate alien-plant-animals absolutely loaded with dark mana. Respond instinctively to stimuli; casually lethal.
4. Shellycoats (Troll Gnomes): remnants of the Necropolis Culture's summoned slaves. Articulated hides clatter and ring. Agonisingly fused into glassy stone by the sun’s rays. Most are small because they don’t get the nutrition or leisure to get big.
5. Mist Drakes: chirruping vaporous things that coil out of the saturated air during the hottest, most humid days. Ephemeral and elemental, superstition holds them to be the ghosts of those who die in and near the Grand Necropolis.
6. Dragon Turtle (1): often mistaken for an island or undiscovered ruins, the Dragon Turtle is one the ancient spirits of the land, and you can only interact with it when it inhales, turning time back to when this was nothing but shallow sea. You've got until it breathes back out to interrogate it and to survive the aquatic dinosaurs and Serpent People mariners.

4. Roll d6:

1. Graveyard Crabs (1-3): tottering giant crabs rumoured to have grown huge on a diet of ancient corpses, but just the natural end of the Sentinel Crab lifecycle - they have grown too big, too fast and cannot sustain the necessary feeding and shedding. They go to ancestral grave sites, where - amidst great drifts of fragile, demineralised remains - they topple over and die. That’s where they’re heading when encountered.
2. Scum Creepers: slimy animate tubers that prey on weak and/or sleeping animals. Actively inedible.
3. Flame Dead: Necropolis Culture undead, wreathed in unearthly flames. Appear either as flickering perpetually offended versions of their living selves, or shrieking candle-wax skeletons. Distant processions of will-o-wisps are said to be Flame Dead pacing the walls of the Grand Necropolis.
4. Grendels/Fomorians: monstrous remnant of the Necropolis Culture; Thouls led/championed by Troll-Ghasts and ruled by Sea Hags (all reskins). Mortality horribly stretched, they require life energy (levels, ability scores) to maintain mental stability.
5. Punkies: halfling-like swamp folk; their lives do not look that attractive from the outside, and considered no better than Goblins by surrounding settled peoples. At least some of them take grim pleasure in decoying biggers into danger; at least some of them eat those they trick.
6. Rusty Derelict (1): counterpoint to Lord Verdigris; decomposed, predatory golem; lubricated with fat, blood hydraulics, and motivated by captured brains. Necromantic engine the likes of which has not been seen before. Haunted.

5. Roll d6:

1. Algal Mummies: weak to air and poison/pollution. Dreamy and meditative, they have become solipsistic druidic monks. Confined to algae-choked flooded tombs, they see through the web of life and animate water-plants to intervene in the breathing world. Think they are the undead remnant of a named individual but really the vehicle of a weird organism.
2. Fungoid Mummies: ornate and bursting with cordyceps-antlers; style themselves as the ultimate form and true inheritors of the Necropolis Culture. Cordial relations with the Mi-Go. Think they are the undead remnant of a named individual but really the vehicle of a weird organism.
3. Gunpowder Beetles heavy and slow; packed with tomb nitre and alchemical waste, warmed by necromantic radiation. Attacked or surprised, they produce a loud crack and a spark of utter darkness (blinding on the mortal sphere, visible on the Astral Plane) accompanied by the stench of brimstone and necrotic damage. Can be harvested and processed.
4. Widow Elves: bereft across centuries, forever mourning long dead mortals. The Necropolis Culture apparently did a brisk marriage business with similarly lost and forgotten Elfish nations, and these grief-mad lamias (and quite probably thousands of fey-blooded ancestors) are all that remain. At least equivalent to your basic Drow in abilities and equipment.
5. Giant Marsh Clams: can you justify a stat-block? Basically, bear traps you can eat and use the shell as a low-quality shield. 2 on 2d6, they’ve been feeding on Psionic Squid for generations and are capable of levitation and mind blast.
6. Dinosaur Ghosts: elementals and thought-forms that pile up in the sky, or loom vast from the mists. Terrifying, spectacular, mostly harmless. Abruptly real when the Dragon Turtle inhales.

6. Roll d6:

1. Lord of Fevers (1): gargantuan processional crustacean-centipede, supported by filmy wings grouped on nodes along its length. Emanations of blast-furnace gut cause radiation sickness. Probably a Larvae of the Outer Gods. Festooned with extra-dimensional parasites. Mostly out-of-phase with the material world; solidifies during Mist season.
2. Pazuzus: wiry, rangy, black manes and feathered wings; refugee demons from the bottom of the pecking order; melancholic because escape has cut them off from the Great Murmuration, choleric because they prefer significantly less earth and water in their environment. 
3. Hippogriffs: beaked and scaly croco-wolves; prefer lonelier hunting grounds as the mammalian predators soundly out-compete them in their niche. Their long-term survival as a species is in doubt, but prolonged by their feeding cycles being measured in months (even seasons) rather than days/hours.
4. Necromancers: apart from the sartorial distinction, they might be any other adventuring party exploring the wilderness. Roll d6: 1 turning undead and not by choice; 2 frosty but non-aggressive; 3-4 untried entry-levels; 5 in possession of something worth taking, whether you know it or not; 6 much too powerful for you to go toe-to-toe.
5. Mi-Go: maybe no more than a small away team across the whole region. Roll d8: 1 following the Lord of Fevers at a worshipful distance; 2 buzzing around the Tower of the Astromancers; 3 observing Lord Verdigris at a respectful distance; 4 taking samples and measurements from Rusty Derelict; 5 retrieving Shellycoat remains with extendable pincers; 6 vacuuming Mist Drakes into compression tanks; 7 containing Thrif in energy bubbles; 8 attempting to communicate with you.
6. Sabre-tooth Woolly Mosquitoes: immortal relicts of what came before the Necropolis Culture. Torpid for millenia, cocooned in something resembling fossilised tree resin; bumbling and mindless through lack of proper regular nutrition, still digesting prehistoric meals from animals long extinct. 3 on 3d6 there's a single Brood Queen waking from torpor, monstrously gravid with parasitic larvae, and capable of reviving the species. For stats, start with a Stirge.

DMR2 Creature Catalog - T & V: Tabi to Velya.

* The Vampire, Nosferatu isn't in the earlier Creature Catalogue (AC9).

Tabi.

Flying monkeys that can be bound (6th level Wizard spell in 2e) as familiars and spies. They are long-lived (though hardly ancient: 150 years in 2e) and give off a stench of rot that can be smelled at up to 100 feet. 

Claws drip a crystal blue venom that causes you to attack whoever's nearest to the best of your ability, but only with weapons or unarmed attacks. Thief abilities. Like to ambush, then hide while their victims fight it out with each other.

I liked this a lot more as just a statblock in the Master DM's book with limited clues to what it was, but I think lots of people have time for winged monkeys (with or without dear little uniforms).

Thunderhead.

Because I'm not keen on the standard dragon, I like borderline cases such as the Thunderhead - a dragon-like fantastic animal that lives in the clouds and loves an electrical storm (encounter one during and it doubles its HD).

Pretty cool.

They're black in colour with a lightning bolt breath weapon, and can carry off a war horse in its claws, so this is a dragon as far as most normal folk are concerned. And I'm not going to quibble.

Topi.

Culturally dubious shrunken undead - smaller (2' tall), tougher and more agile (they can jump) Zombies with slow venom. The process of making them is known only to certain primitive tribes, because head-hunters or voodoo or something.

Caricatures aside, I think they're a sound little monster and a sound little statblock for reskinning. I especially like the inclusion that hitting them with a bludgeoning weapon knocks them over and they lose their next attack.

2e uses tribal, witch doctor and shaman to indicate the certain primitive tribes aspect, and includes the usual greater detail for creating one and how its abilities interact with the expanded AD&D rules. They also get a slight boost in intelligence, making them capable of carrying out orders without close supervision and taking pleasure in killing.

Tortle.

Terrapin/tortoise/turtle people. See also, Snapper. Apparently quite popular nowadays.

Can retreat inside their shells for (in CC) undefined protection. You can use the shells of 25 of their freshly harvested eggs to make lightweight plate mail armor. And they prefer to travel on horse-drawn wagons when not bobbing along in the water.

They travel to traditional, stone-walled compounds near the end of their lives to lay eggs, barricade them in, and then die. Doesn't say if this happens en masse or individually, but I find the whole thing conjures a somewhat bleak image.

2e changes this to females lay eggs only once during their lives and aging males then watch over the eggs, dying once they are safely hatched. Which is also kind of bleak. Though the text would imply that the other Tortles stick around (maybe having a carnival or solemn rites) rather than leave the eggs and the elderly, I think I'd lean into the bleakness on this one.

I like them more than I would expect now I've considered their lifecycle. 

Triton.

Higher (5 to 7) HD merfolk with level-equivalent spell-casting ability (50/50 Cleric or MU - no fire spells). Sparse cultural/habitat detail - they braid their hair and build cities that are works of art.

Different enough to the MM that you could use both. They could share tridents.

Vampire, Nosferatu.* 

This is a special vampire, in that it's the more traditional blood-drinking rather than level-draining one.

Surprisingly short compared to almost every other Vampire entry in almost every other game.

Guess what? Turned as a Vampire by Clerics.

There's a version in 2e, but it's part of the Ravenloft setting. There are a number of differences, not least that it has mechanics for blood-drinking, rather than merely a d4 bite and dietary preferences.

Vampire Rose.

They flush red from white after they've fed on d8 hp of your blood per round. Save vs. spells or you are hypnotically anaesthetised (so I'm not clear if this is a chemical or a magical effect) and let them do it.

They can uproot themselves and move about, albeit slowly, which is creepy.

2e states that the hypnotic effect is from the plant's fragrance, and adds the wonderful feature that it screams and spurts blood if you can sever a part of it while it feeds. Save vs. fear if this is the first time you've experienced this.

Now one of my favourite plant monsters.

Velya.

Take a Vampire entry (almost any will do). Swap around what they can turn into (shark, ray, water) and what they're particularly vulnerable to (destroyed by exposure to open air), but they're otherwise much the same (the Velya has a weaker statline).

However, that doesn't mean I don't like the Velya. In fact, I've always thought it was pretty cool. 

Its charm person power is a thematically appropriate song, and they're normally accompanied by 1d6 wights (victims return as Wights, not more Velyas).

There's also a swamp variant of this variant (turns into albino croc, white eel, water; not vulnerable to open air, as long as it's in contact with the swamp).

As featured (with Wight; by Jeff Butler) in X7 War Rafts of Kron.

CC has them as the undead of surface cities that have sunk beneath the waves; 2e suggests an ancient curse. Maybe this could be what happens to you when you badly disrupt a Shark-kin ceremony and prevent the new elder's ascension.

For some reason, both CC and 2e seem to have settled on that Wight rather than the actual Velya for inspiration: