Free Yuan-ti Adventure: The Ophidian Lord

Dodge sneaky snakes and snake-y people in our free yuan-ti adventure: The Ophidian Lord!


I like to consider myself pretty well versed in Dungeons & Dragons lore, but there’s definitely a few blind spots for me. I can’t begin to name the number of times I’ve included mainstay monsters like mimics, beholders, or rust monsters into campaigns, but certain monster groups have never exactly been on my radar. So for this month’s Side Quest, I wanted to let my patrons vote on three groups of monsters that I had very little working knowledge with to challenge myself. Between giants, duergar, and yuan-ti, the evil snake people won the popular vote! So with that I’m happy to present this free yuan-ti adventure: The Ophidian Lord!

For those of you who are new to our blog, Welcome! We post a monthly Side Quest, which are short, free TTRPG encounters with corresponding maps that can be easily threaded into an ongoing or one shot campaign, allowing busy DMs to throw in a random encounter at the drop of a hat. Our Adventurer Level 2 tier allows our Patrons to pick the game system, theme, and name a character or two in an upcoming Side Quest. We create a free adventure around their idea, and now everyone gets to enjoy this free Yuan-ti adventure! Plus, Patrons receive a downloadable version of all our Side Quests.

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Free D&D Yuan-Ti Adventure: The Ophidian Lord

For Adventurers level 7-8


Few alive today know of Col’tezal, the Ophidian Lord. Col’tezal was once a demigod of a long forgotten civilization, beloved by the people. Over time, Col’tezal became bored by the mindless adoration and began performing bizarre rituals in secret. These rituals twisted the bodies and minds of captives and servants alike, warping them to reflect the aspect of serpents, which pleased Col’tezal. A small group of heroes caught wind of Col’tezal’s deeds and, with the aid of good-aligned demigods, sundered his temple and minions. Col’tezal was not slain in this upheaval, but reduced to a weakened, slumbering state in the lowest chasms of his once mighty temple. 

Strange whispers circulate in the darkest corners of back rooms and underground chambers, bringing weak-minded folk to the preachings of Col’tezal. A cabal of cultists recently located the sundered temple of Col’tezal from these whispers, and are now working towards reviving him through ritualistic sacrifice. It is only a matter of time before Col’tezal walks the lands of mortals once again. 

Plot Hooks

  • An NPC related to the party is captured by the Yuan-ti cultists, leaving only a tattered map leading to the sundered temple.
  • A renowned explorer requests the aid of the party to protect them while they uncover archeological secrets in this newly-unearthed temple.
  • A patron deity bestows a vision upon the party, warning them about a sundered temple and a growing peril within.

Reaching the temple

The sundered temple of Col’tezal lies far from the trappings of civilization. It takes an average of two weeks of overland travel through snake-infested terrain to reach the site. Col’tezal’s sleeping influence controls a number of creatures in the area that act as guards for the demigod. Consult the table below for possible random encounters while en route to the temple.

  • d1. 1d4 giant constrictor snakes
  • d2. 4d6 poisonous snakes and 2d4 constrictor snakes 
  • d3. 1d6 Yuan-ti broodguard
  • d4. 1 Yuan-ti malison and 1d4 swarms of poisonous snakes
  • d5. 3 Yuan-ti malisons
  • d6. 1 Yuan-ti abomination and 1d4 cultist

Temple of Col’tezal Overview

Temple Exterior

Giant trees emerge from the uneven ground around the remnants of once great stone structures. Vegetation overtakes the stone path leading to different buildings around the area, and tangling vines easily trip the unwary. Beams of light filter down through the massive leafy canopy above which provide only dim light during the day. Most of the above-ground structures are empty aside from overgrown vegetation and long-rotten fixtures, though some determined explorers might find a handful of dirty coins. 

Yuan-ti cultists use a combination of debris and magic to hide the temple entrance from sight. Searching for an entrance requires a successful DC 16 Intelligence (Investigation) or Wisdom (Perception) check. Alternatively, characters casting detect magic spot an aura of illusion magic (hallucinatory terrain) over a section of the ground near a collapsed building. If the party decides to wait and watch the entrance or area, one yuan-ti malison, one yuan-ti cult fanatic, and two yuan-ti cultists leave via the illusion. They attack intruders on sight unless the party hides themselves ahead of time.

General features

The interior of the temple is made entirely out of worked yet crumbling stone, with ten-foot-high ceilings. The smell of earth and moisture is pervasive, as areas around the temple see the ceiling collapsing as tree roots dig their way deeper underground. Cultists keep braziers lit in certain areas which provide bright light in a twenty foot radius. Doors are made of stone slabs reinforced with metal and are unlocked unless otherwise noted.

Y1. Entry chamber

The mouth of the temple entrance slopes into the earth and descends fifty feet down before leveling out into a 15 by 15 ft room lit by two braziers. Two carved plaques embedded into the wall depict odd images of snakes turning into men and razing a town.

Y2. Overgrown hall

The hallway splits in two directions: to the west a sloped ramp leads down ten feet to another closed stone door, and to the south into a large hall. The root system of a massive tree grows from ceiling to floor, breaking up the stone tile beneath. Two lit braziers flank a carved plaque upon the wall.

Stone plaque. Characters proficient in the history skill may attempt a DC 15 Intelligence (History) check to recall information about the temple and its purpose. On a success, they learn that the temple is the lair of the great Ophidian Lord Col’tezal, whose arcane knowledge frightened civilizations past. 

Snakes in a tree. Two swarms of poisonous snakes live within the tangling roots of the tree and attack any non-yuan-ti that attempt to leave the room.

Slope trap. This stone slope rests at an easy angle, one shallow enough to allow the snake-bodied yuan-ti to descend with ease. Perceptive characters (passive perception of 18 or higher) notice that slight wear on the slope favors the northern side for the first five feet, then the southern side for the last five. Any creature that steps off the worn area must make a DC 16 Dexterity saving throw as holes open up underfoot and launch metal spikes upwards then quickly retract. Creatures take 2d10 piercing damage on a failed save, or half as much damage on a successful save.

Y3. Collapsed passage

Multiple trees grow within this large passageway, ripping up stone along the floor and ceiling. Simplistic scaffolding rests against the walls in an attempt to shore up weak points. The stone plaques upon the walls are illegible. Three yuan-ti cultists, two yuan-ti pureblood, and one yuan-ti malison work within the room. If it appears that they will lose a fight, a pureblood will attempt to run to the storage room (Y5) and warn the cultists there.  

Weak ceilings. The cult has made great strides in repairing certain areas of the sundered temple, but this passage requires much work still. Any attacks or spells that create loud noises or deal thunder damage weakens the supports and causes parts of the ceiling to collapse. Creatures within ten feet of the instigating sound must succeed on a DC 12 Dexterity saving throw or take 1d12 bludgeoning damage and become blind for one round as falling debris temporarily blinds them. 

Treasure. The cultists work with two complete sets of mason’s tools and carry 63 gp, 34 sp, and 10 bp between them.

Y4. Storage

The yuan-ti cultists keep a majority of their daily supplies within treated wooden boxes and barrels scattered around this room. Vines grow from dark soil in the western corner of the room and seemingly reach towards some nearby barrels. Two yuan-ti broodguard stand watch over a yuan-ti cult fanatic as they take stock of the supplies. A closed stone door sits within the eastern wall.

Enchanted vines. The vines count as difficult terrain, and any creature that attempts to move through must succeed on a DC 12 Strength saving throw or becomes restrained by the vines as they quickly grasp at them. 

Treasure. Food and water keep well within the special containers that are meant for humid environments. Anyone searching the boxes finds 20 days worth of rations, as well as enough fresh water for another 20 days. The other containers hold worthless sundries. The cult fanatic carries a jeweled dagger worth 125 gp.

Y5. Underground tunnel

Two braziers light the entry of this room and cast dark shadows on the far walls. A ten-foot diameter hole sits in the middle of the floor and slopes downwards at a steep angle. The sides of the hole are made of compact dirt and occasional bits of stone and root. The hole descends fifty feet at an angle to another room (Y6). A creature may climb back up the tunnel at 10 feet a round, or move at full speed on a successful DC 12 Strength (Athletics) check. Creatures with a climb speed may move normally. 

Disturbing plaques. Five stone plaques reside upon the walls of this room, each depicting a different victory or arcane advancement that Col’tezal made. Each plaque is more grotesque and disturbing than the last. Any creature that attempts to read all of the plaques in the room must succeed on a DC 16 Wisdom save or they gain the frightened condition when they enter the altar of ophidian lord (Y10) and behold the mighty form of Col’tezal. Once triggered, this condition lasts for one minute.

Y6. Serpent’s passage

The simple tunnel deposits characters into a gloomier passage that is lit by two braziers, yet the shadows dance and move ominously beyond. A wide stone slope descends to the east, while a closed stone door resides to the west. Two stone statues of snake-headed humanoids stand at attention against the southern wall. 

Yuan-ti statues. The statues are two yuan-ti malisons enchanted with a disguise self illusion to appear as solid stone statues. While they remain motionless, they are indistinguishable from a normal statue. They attack if the party lets their guard down or if attacked first.

Y7. Sleeping quarters

Four basic beds fill these spartan sleeping quarters. Three shelves hold a number of utensils and supplies, while a table sits near the southern wall. Two yuan-ti cult fanatics sit and tend to daily chores. 

Treasure. Searching the quarters over the course of ten minutes reveals a small pouch holding a gold hair comb worth 45 gp, a beautifully cut topaz (150 gp), and 73 gp. Succeeding on a DC 18 Wisdom (Perception) check reveals a hidden compartment underneath one of the beds which holds a wooden box with 7 pinches of dust of dryness within.

Y8. Cobra shrine

Just around the corner from the base of the stone slope reside four expertly carved statues of cobras with rubies for eyes. Each statue stands five feet tall and looks directly across at its counterpart. Four stone plaques rest on the walls behind the heads of the cobra statues. A stone door sits at the end of the hall, while another door resides at the end of a hallway to the west. Both doors are locked.  

Cobra statues. These stone depictions of cobras sit upon small turntables and rotate with a little effort. If all four statues are moved to look at each other in a cross position (see image below) — the door to the west unlocks with an audible click. The statues are impervious to damage and cannot be lifted. 

Disturbing plaques. Four stone plaques reside upon the walls of this room behind the cobra statues, each depicting a different victory or arcane advancement that Col’tezal made. Each plaque is more grotesque and disturbing than the last. Any creature that attempts to read all of the plaques in the room must succeed on a DC 16 Wisdom save or they gain the frightened condition when they enter the altar of ophidian lord (Y10) and behold the mighty form of Col’tezal. Once triggered, this condition lasts for one minute. 

Secret door. A long-forgotten door hides within the northern wall of this chamber. Eagle eyed characters can detect a faint door seam on a DC 25 Wisdom (Perception) or Intelligence (Investigation) check.  It will only open if all four cobra statues are aimed towards the north wall.

Y9. Wild sanctuary

The door leading to this room is magically closed via arcane lock. It will open with a key that resides within the altar room (Y10). This A-shaped room smells strongly of musty earth and grime. Roots rip through the stone walls and ceilings in the nearest alcove as vines creep along the floor. The furthest alcove holds a rune-inscribed circle engraved on the floor that emanates a soft yet menacing glow. 

Captives. Six humanoid captives sit in the eastern alcove of this room. Each one looks in rough shape, with bruises and cuts, but is otherwise whole. They are chained to each other with the chain connected to the nearby wall. A DC 22 Strength (Athletics) check rips the chain free. They do as asked as long as they are guided out of the temple.  

Ritual plaques. Two stone plaques reside upon the walls of this room, each depicting a ritual process to transform humanoids into snake-like hybrids. 

Ritual circle. This magic circle is used by the cultists to slowly convert captives into the broodguard used for defense. No immediate harm befalls any creature that steps into the circle without a cultist nearby to enact the ritual. The ritual circle can be destroyed with dispel magic at DC 18.

Y10. Altar of the Ophidian Lord

The largest of the underground chamber dwarfs the rooms that came before. The ceiling rises to twenty-five feet tall. A ten-foot-wide stone bridge crosses a chasm in the middle of the room that drops off into murky darkness. The sound of rushing water can be heard from below. Beyond the bridge a stone altar sits between two lit braziers as a yuan-ti cult fanatic screams the final words in a hissing dialect. The fanatic is flanked by four cultists clad in robes of gold and green. They do not immediately react to any intruders, only focusing on completing the ritual to summon the Ophidian Lord, even if they begin taking damage. After the ritual completes, they attack any intruders. 

Col’tezal, Ophidian Lord. As the final screams echo through the chamber, low rumblings grow deep within the pit. Within two rounds, a massive snake-headed bulk hauls itself up and onto the bridge in the center of the room. This multi-headed serpent is the reincarnated form of Col’tezal. Col’tezal uses the stats of a hydra with the following changes:

  • Col’tezal starts with six heads, instead of five. 
  • Due to it’s reborn state, Col’tezal’s AC is 14 and it rolls 1d8 for damage (instead of 1d10)

Col’tezal makes no distinction between friend and foe, striking out at any target within reach, including the cultists. The cultists focus on the party, and will not harm the hydra due to their blind devotion. 

If the party attempts to flee the room, Col’tezal bursts through the wall and pursues the interlopers, causing massive damage to his own temple. 

Col’tezal fights to the death, screaming an unworldly shriek as his spirit departs the beast’s flesh. Any remaining cultists drop to the floor in shock and become unresponsive to any provocation.

Chasm. Any characters unfortunate enough to fall into the chasm in the middle of the room plummet fifty feet down into a pool of deep water. Creatures must make a DC 10 Dexterity (Acrobatics) check to avoid damage. Failure causes a creature to suffer 4d6 bludgeoning damage from the fall, while a success only deals half as much damage. The walls of the pit are steep but rough, and a creature may attempt a DC 12 Strength (Athletics) check to climb back up, moving 10 feet per round on a success, or 0 feet on a failure. 

Treasure. The cult fanatic holds a jade and copper medallion of a snake eating the sun worth 300 gp. The stone altar holds multiple ritual pieces, including a gold snake idol worth 500 gp, four brilliant diamonds worth 100 gp each, and an elemental gem (blue sapphire/water elemental). A key to the wild sanctuary (Y9) also rests upon the altar.

Y11. Forgotten library

Dust and cobwebs hang from nearly every surface in this room. Gold-reinforced wood bookshelves line the walls and are filled with books of all kinds of shape and size.  Carved into the eastern wall resides a singular stone plaque, its face covered with grime.   

Treasure. Most of the books and trinkets within this room are worn with age, but some still hold value for collectors. Twelve books from different long-dead authors sell collectively for 600 gp, a crystal orb with gold leaf infused to its surface (125 gp), a rod of rulership rests atop one shelf, and a dagger of venom stands embedded in a book. In addition to this treasure, multiple spell scrolls are distributed around the room: 

  • Two 4th-level spell scrolls
  • Four 2nd level spell scrolls
  • Two 1st level spell scrolls


With Col’tezal slain and his cultists routed, the preternatural gloom lifts over the region and the insidious whispers cease, for now. It may not be for another millenia, but Col’tezal may once again speak into the minds of like-minded fools and begin the process anew. However, slaying him will fall upon another group of heroes in times to come.


And that’s all for this month’s Side Quest: The Ophidian Lord! I hope you all enjoyed this Free Yuan-Ti Adventure and we would love to know how you use or adapt this adventure, so please drop a comment here on the blog, on Twitter, Facebook, Instagram, or Discord to let us know how it went! If you’d like access to more maps and content, including downloadable PDFs of our adventures, check out our Patreon. We’re able to do what we do because of all our amazing Patrons!

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