Monster Of The Week: The Neogi

Legacy In The Fleets Of Spelljammer

Aberrant, magical beasts of arachnid legs and eel bodies, the Neogi are another remnant of a more alien dungeons & dragons experience.  Often described as the blend of a wolf spider and a giant eel, Neogi are monstrous to behold.  These telepathic, mind-controlling masters of intellect and technology once roamed the extraplanar space and time of the Spelljammer ethos.
  A society built upon cunning, opportunity, and devious plots, these aberrants sought power and prestige among the stars.  Their ships, often called Mindspiders, drifted through the Astral Sea, or its legacy name - The Sea Of Night, within the Realmspace (a whole other fascinating can of illithid).  Some of their ships could even shift into other planes, and prey upon the Githyanki and Djinn vessels across known space.

-- A Neogi Mindspider, primed for assault --

Might and Magic

As with all intelligent societies, the Neogi have a curious relationship with their gods and their roles.
  Gender is not a thing in Neogi society, a fact that extends to its deities.  These entities are more complex; built from the concert of certain barbaric ideas.  For example, one deity personifies torture, pain, and suffering; while another stems from the chaos of creation; still another is fueled by envy or jealousy (the Neogi's understanding of "love").
  But the Neogi's relationship and interpretation of these entities is particularly interesting.  Unlike many other societies, Neogi culture dictates that the gods of their pantheon do not take tribute from their followers; it is very much the opposite.  These mythic creatures are instead demanded favors and boons regularly; these gods, the Neogi believe, are merely servants of the Neogi race, and therefore MUST provide.  For a deity to fail in this endeavor would mean their destruction, and devouring, as another more powerful "servant" would take their place.
  However, the Neogi, always primed for chances at greater power, would not settle for their servant gods.  In their journeys across realms, Neogi shamans (warlocks) would strike pacts with the powerful entities they came across - most notably some of the literal Elder Evils of D&D's legacy: Acamar, Caiphon, Gibbeth, and HADAR (you heard me).  They took these greater beings on as mentors and helped further their influence in the known and unknown cosmos.

Science and Industry

Though their bodies and visage would lead one to believe only in a monstrous, primitive society, the Neogi are highly advanced in many studies and disciplines.  The stratification of roles and duty can even be observed in how they paint or tattoo their furry abdomens, certain colors denoting specific trades and responsibilities.
  With little empathy for other creatures, the Neogi are accomplished "flesh weavers" and necromancers, using the parts and pieces of numerous other species, slaves, and failed experiments to produce terrible and fascinating new monstrocities.  It is rumored among Loremasters that these arachnid "mad scientists" are responsible for the creation of the Gray Render...  Though no others can prove such a claim.  The poor Umber Hulk and its cousins have been summarily studied, dissected, mutated, and raised from certain death by these practices, the dreaded Undead Hulk - an Umber Hulk flesh golem of regenerating pincers and necrotic spray - finding a home as both a Neogi guard dog and their prime enforcer.
  Aforementioned warlocks and the few wizards of their clans were both motivated and industrial, forging new and modified versions of spells to adapt and support their war parties, and extend their dark rituals.
Speaking of rituals - this is how more Neogi are created.  You see, as a Neogi reaches the end of its life and its memory begins to fade, a Neogi Priest will inject a powerful venom into the aging Neogi and perform an ancient ritual.  Usually small or medium creatures, this elder Neogi will swell to a 20-foot behemoth called a Great Old Master.  This mutated creature will remember nothing of its old life and will be driven only to eat, growing as large as possible.  Those with Feeder striations in their fur must now gather as much food for the Great Old Master, as it eats and creates eggs inside its massive body.  After two months of growth, the eggs hatch, killing the Old Master.  The 20 to 40 new Neogi spawn then feed on the Old Master's corpse...and each other, until the strongest of the cluster survive.

By The Numbers (5th Edition)

In 5th Edition Dungeons & Dragons, you'll likely run across the Neogi in three forms - the Hatchling, the standard Neogi and the Master.  Let's break them down.

HATCHLING (tiny) - young and fledgling (AC 10-11; HP Level 1 Wizard), these are dangerous in large numbers and simple on their own.  Just don't wake up their older siblings.
NEOGI (small) - better natural armor (AC 15-16) and multi-attack makes this bugger a tougher beast to tango with, but this standard beastie comes with the main thing that makes these critters tick.  The Neogi has an Enslave ability (Short or Long Rest dependent) that pushes a Wisdom save.  Fail that, and you're charmed by the creature for one DAY (and it knocks out your Reactions - bummer).  Oh and did I mention that the Neogi talks to you telepathically during this whole thing out to a distance of one mile?  *shudder*
MASTER (medium) - not to be confused with the "Great Old" variety, these nasty variations on a theme get everything their small counterparts do (plus more than double their HP pool), and are freaking spellcasters!  Looks like these masters went all in for the Hadar fan club with a slice of Confused Bard, so be ready for some telepathic Vicious Mockery while being whalloped with Eldritch Blast for good measure.  Be careful too, they can function as a 7th-9th level caster, so that spell save may be meaner than you think at low level.  And I know I mentioned the "Hadar vibe", but any DM that does their research can mix up that power set to match another Elder Evil (wink-wink).

Now, each of these creatures has the Mental Fortitude of an Elf and Spider Climb, so watch your six.  What they lack in empathy, they make up for in numbers, and if they're following that Spartan Chuck-E-Cheese childhood, you can bet that what's coming for you ain't no pushover.

Closing Thoughts and Interpretations

The Neogi are a Legacy Monster.
  Given their expansive and extensive lore dating back to second edition (2e), not to mention their pronounced influence within the Spelljammer history, their current iteration and inclusion feels lackluster.  There are dozens of fascinating creatures with deep history and ethos in Faerun and worlds beyond that are offered only a tiny passage in Volo's Guide, or Mordenkainen's Tome, or the Monster Manual talking about them, and, unfortunately, many of these passages end with a "nobody really knows" and a shrug (flips page).  
  To say that these are missed opportunities isn't exactly fair, either.  At its core, 5th Edition is intended to be accessible.  You don't want to bury the DM in mountains of back-logged history (some of it quite problematic today) just to get an interesting critter on the board.  So instead, I offer up my own approach:
This awesome monster can be a one-off.  A "well, that was weird, moving on" type moment.  OR, much like what happens when I do my research for each of these, this monster is a launching point of inspiration.  Truthfully, I hadn't yet considered the Neogi's place in my homebrew setting, but you can BET I've got one mixing now.  The rabbit hole I jumped into has some really cool avenues to play with, and I can twist and turn and mutate them however I see fit.
These things have a huge spider motif going for them - could they be distantly connected to Lolth?  Maybe the Drow that serve her hate Neogi, because they believe their banners as an affront to their queen!  You don't know (shrugs and cackles in DM).  
  My point is that for every moment of disappointment found in a feature, creature, or spell, there can instead be a tiny mote of inspiration, leading you to a setting with greater depth, immersion, and personal craft.

Happy worldbuilding.
​-Adamus