141 The Sylvanboros


About this Resource

This resource features the general description of a monstrous Feywild entity visiting the Material Plane. It includes adventure ideas that are appropriate for low-level (Levels 1 to 5) adventuring parties. Challenge Rating (CR) is calculated using a party of four as the model.

The DM is free to change or modify any or all the information found here. NPC names and settlement names are the first the DM should consider changing to accommodate any homebrew world lore. To modify the challenge rating of the adventure, the DM must first consider the power level of the party. Considering the PCs’ individual levels and number of players is crucial to presenting a good challenge. Not all parties are the same, different playing styles and command of the system in the party can increase or decrease their effectiveness in encounters. The DM may adjust the encounters slightly by adding or subtracting monsters. Alternatively, controlling monsters with more intelligence and strategy is often the easiest way to raise the difficulty of an encounter.

When monsters are referenced, book name and page numbers are noted in parenthesis. Be aware that page numbers may vary depending on the book print. If the DM can’t find a monster where noted, it means it is a different book print. Page differences tend to be small so whatever is missing will be reasonably close to the pages noted within the adventure.

Background Lore

Dr. Luca d’Fanne was a renowned explorer and zoologist. He died fifty years ago from a wound in the field. A venomous spider incorrectly identified and catalogued bit him in the left arm; Dr. Luca expired a few hours later. His work on zoology and anatomy of wondrous creatures is beyond value to sages, librarians and other students of science. Dr. Luca d’Fanne had a knack for tracking creatures and luring them to traps. He often captured creatures for a few hours or days to study them. He would then free them back into the wild. Dr. Luca often hired other explorers and able rangers to come with him on his expeditions; he was not unaware of the danger he put himself and others into, but he believed science and discovery could only be fueled by brave scholars. Everything was out there ripe for taking, but you had to take the first step.

There is one work which gave Dr. Luca his reputation. The study of the elusive Sylvanboros. The strange creature was part of local myths and legends and there were only a few old people who claimed having seen it over sixty years before.

Dr. Luca identified written records of the giant creature’s sightings with almost clockwork precision: every sixty seven years and 5 months the creature appeared in heavily forested areas for a few weeks. Being fascinated by cosmic planes and other dimensions, he discovered that the Sylvanboros appeared when the Material Plane and the Feywild eclipsed each other. A cosmic event that occurs every sixty seven years and that brings the planes closer than they already are for several weeks. It is known that certain areas physically link to the Feywild, opening temporal pathways to and from the sibling plane. With this information, Dr. Luca d’Fanne determined that the next appearance would happen in eight years and it would be the only chance to study it during his lifetime. He gathered a group of brave explorers and set out to find it when the appointed time came. They all traveled to an old great forest, ventured in and made camp near the center of it. They stayed deep in the forest for weeks, waiting for the creature. They knew the two planes were linked because of the influx of creatures and being not native to the forest. They even encountered a pack of satyrs, sometimes referred to as fauns; they were on a pilgrimage. Dr. Luca d’Fanne could not communicate well with them, however. None in the expedition was fluent in sylvan, Dr. Luca only knew a few words and phrases.

The Sylvanboros eventually showed itself to them. As detailed in Dr. Luca d’Fanne’s books, some Feywild are actually spirits. These spirit take on physical forms and the shape they take depends entirely on the nature of the spirit. The Sylvanboros is one such creature, the fey spirit represents the eternal cycle of the food chain. How every being, sentient or not, occupies a specific niche in it. Every animal is some other animal’s food; even the great carnivores on top of the chain eventually expire and are eaten by insects and worms. Every being eats and leaves behind feces that go back to the ground and feed plants and the cycle starts once again. The Sylvanboros takes the form of a giant snake-like creature. It measures two-hundred and sixty feet long and almost thirty five feet tall in its tallest point. It is not particularly fast but it roams the land eating everything in its pass: animals, trees, the soil and rocks. Everything is eaten, digested and then processed. Any digested materials are then expelled from the creature through its outer sphincter, the remaining material appears to be fresh wet soil, enriched with organic material. Even though the Sylvanboros is able to decimate a forest, after it goes back to the Feywild, the forest always grows back bigger and stronger.

Dr. Luca d’Fanne and his chief explorer did the bravest thing and went inside the Sylvanboros. The great snake is not aggressive. I t knows no predator or danger to itself, so it mostly ignores anyone who approaches. It even welcomes any who comes close enough by opening its jaws, a free passage to digestion. After the jaws and the throat, they found themselves in a wide chamber where the Sylvanboros spirit manifested itself as fighting snake people. The snake people were similar to the feared Yuan-Ti,             with some differences: these were just projections of the fey spirit’s will. The snake warriors vanished in vapor and smoke when killed. After crawling through a sphincter, they found themselves in the stomach, a pool of acid. Despite the great snake moving, all acid stayed on the bottom of the chamber. After closer inspection, they discovered that the acid was not entirely liquid, it was more like gruel, dense and sticky.

The stomach chamber was faintly illuminated by a red light coming from two holes on the chamber’s ceiling. It took Dr. Luca and the other explorer some tries with ropes and hooks to climb up there. They found the heart cavity. Dr. Luca d’Fanne found it curious that a spirit would manifest a physical heart but no lungs. It certainly did not have a need for any of them but the heart was in front of him, pumping blood to the impossibly huge creature. They tried coming closer to the heart but it defended itself against them. Through some elemental magic, the heart created spell-like effects to keep them at bay. Dr. Luca decided to leave the place, return to the acidic stomach and continue down the intestines.

The intestines are winding short tunnels that crushed anything within them every few seconds like relentless hammers. Only a small area was crushed at a time, the walls closed in on themselves like a slow wave that ended in the outer sphincter. Dr. Luca d’Fanne managed to escape but his companion died crushed. He felt lucky, no other human had ever studied the Sylvanboros from up-close, he even managed to see the innards of the fantastic creature. Years later Dr. Luca’s schematics and drawings of the Sylvanboros became a source of fascination for other scholars and zoologists. The circumstances guaranteed that Dr. Luca would be the only one to ever have experienced it because the great serpent would not be back to the material plane for a long time.

The Sylvanboros

The legendary snake is peaceful in nature, but it’s path and actions can wreck forests and settlements. A great way to introduce this creature to an adventure is to have the adventurers stationed at one such settlements in danger of being overrun and eaten by the Sylvanboros. This would mean that the adventurers are present at the exact moment when the two planes come together. Settlements appropriate for this would be placed inside a forested area or right outside. While the adventurers are present, scout reports alert the townsfolk of the impending danger. Depending on the size of the town, a sum of gold or equivalent reward is offered to brave warriors who manage to either kill the thing, or make it change its path. The DM is free to insert the background lore in the form of a local legend or by having someone produce Dr. Luca d’Fanne’s book about the great beast.

  1. Entering the snake

The Sylvanboros is slow, its speed is 10 ft. Adventurers only need to approach the Sylvanboros for it to open its mouth and let them in. The great serpent’s outer body is covered in hardened scales. No weapon can harm the fey spirit.

  1. The Esophagus

The esophagus is littered with remains of other things the Sylvanboros has recently ingested. As soon as a living creature enters (such as the adventurers), four creatures emerge from the walls of the esophagus. They are humanoid but have scales and heads of snakes. The DM is free to use a modified version of the Yuan-Ti Pureblood (Monster Manual p. 310). Modification is only needed for very low level parties; they DM should consider reducing HP to half its noted value and dispense with the Innate Spellcasting. Number of creatures for this encounter depends on party size and level.

  1. The Stomach

The stomach chamber is 45 ft. long. There is a 10 ft. deep pool of acid; the acid is thick, only heavy objects sink to the bottom, other things float while they are dissolved. There are two orifices in the ceiling that lead to the chest cavity, a reddish light comes from them. The PCs will have to be creative to climb up there and to cross the pool to the other side. There is no default method to do this but the DM should reward player creativity when the players suggest possible courses of action. Any character that falls to the acid pool starts to slowly sink, When a character falls on the think acid, he takes 7 (2d6) acid damage. The damage occurs again at the beginning of the character’s turn for as long as he/she is submerged. Escaping the acid is no easy task due to the thick nature of it. A character attempting to swim out of the acid must succeed on a DC 15 Strength (Athletics) check to either reach the esophagus sphincter or the intestines sphincter.

  1. The Heart Cavity 

The heart is the physical representation of the fey spirit itself, the serpent does not need it, nor does it pump blood. Faint whispers in the sylvan language come from the heart at all times. The PCs can attempt to attack the heart to “kill” the Sylvanboros, or persuade it to change its current course. Attacking the heart starts a battle sequence. The heart has AC 15 (natural armor) and HP 70 (adjustable for party size and level). The heart rolls two initiatives and can thus acts twice per round. The Sylvanboros’ Heart cannot physically attack but it can manifest certain spell-like effects. This is the spell list available to it: Shield, Magic Missile, Charm Person, Entangle, Fog Cloud, Heat Metal, Hold Person and Shocking Wave.

Once a battle starts, the heart casts Entangle and Fog Cloud to restrain and disrupt the PCs. If it gets surrounded it can cast Shocking Wave, potentially causing a PC to fall through an orifice down to the pool of acid. Charm Person is useful to split the party. If the heart is defeated, the Sylvanboros stops moving and starts to expire. The fey spirit cannot be killed, it simply is sent back to the Feywild. Though the creature is dying, the adventurers still have to escape the snake. Exiting through the mouth is impossible, the jaws are closed and too heavy to lift. The PCs must go through the intestines to the outer sphincter. While the Sylvanboros is dying, the intestinal activity continues and the PCs must still be careful not to be crushed.

If the party decides to negotiate with the Sylvanboros they must find a way to communicate in Sylvan, it is the only language the creature understands. The Sylvanboros is not evil but it also does not care what is in its path. It could change its course at any given time but the PCs must provide a good reason to do so. Alluding to innocent people in danger or other things that would be destroyed are not convincing arguments for the fey spirit. The DM is given complete freedom to determine what is a convincing reason for the serpent to accept. If the party manages to convince the Sylvanboros to change direction they still have to find a way out through the intestines.

  1. The intestines

The intestine walls are rough. They close in and crush anything inside every few seconds. Not all sections of the intestines are crushed at any given time. An adventurer braving this part of the Sylvanboros must be quick and determined to be able to exit. The outer sphincter opens each time the last section of the intestine closes on itself, pushing anything or anyone out. Each adventurer trying to cross the intestines must succeed on a DC 14 Dexterity (Acrobatics) check to cross safely. The DM is free to determine whether a single or several checks are needed to make it to the end safely. A character who fails the check is crushed by the intestine walls and takes 10 (3d6) crushing damage.

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