Secrets in the swamp

Adventure background

This oneshot is meant to be used with the 5e and is designed for a party of 5 of level 7.   This oneshot can actually be added into any campaign as long as the group is travelling through a swamp.If it is run as a oneshot the group will start as members from The Vanguard. They receive a mission briefing at the Vanguar headquarters near Edron.     Normally the road between Edron and Torini is quite safe but recently many travelling merchants have disappeared. None of the missing people have even arrived at Niravi. The Vanguard therefore thinks that something is afoot near the edge of the Endra Swamps. The group will leave the Vanguard fortress and travel the road towards Niravi to investigate.  

Swamp's Edge

  Normally the group will not have any issues reaching the part of the road near the edge of the Endra Swamps. However, if needed an extra encounter can be added after the group passes Edron. Roll 1d6 to see what the PCs encounter.
Roll Encounter
1-2 1 giant crocodile
3-4 1 Shambeling mound disguised as a bush near the road
5-6 A swarm of weird looking purple birds in with parts of their bodies covered in scales. They are not hostile an fly away when attacked.
  None of these creatures are actually supposed to be here. In recent times there has never been a report about them. They however, do not seem to be the main reason as to why people disappear. The group would better continue forward to see if they can find anything more.  

Get outta my swamp

  Once the PCs reach an abandoned caravan read the following:  
After travelling for some time an abandoned vehicle can be seen further away along the road. Once the group comes closer they can cleary see that it is a cart with a tattered cloth roof on top. Further along the road there are several other carts but no sign of life. It does not take long, however, to see the large amount of blood spread across the ground.
Swamp Encounter
  To try find out what happened the PCs can make an investigation check.  
Roll Result
1-12 The PC finds the signs of struggle and the amount of blood but can't find out much besides that the drag marks point towards the swamp.
12-18 By carefully looking at the area the PC finds that these marks on the ground are definitely not caused by a human. Even more some of the tracks in the mud even suggest that it was a large create with tentacles.
18+ The PC also notices something moving in the water nearby. They will not be surprised by the creature. If they mention this in time to the other they will not be surprised as well.
  The group will be attacked by a strange and alien looking creature whether they noticed it or not. This creature seems to consist mainly out of tentacles with its much smaller body hidden behind the tentacles. The head has no eyes but has a large mouth filled with razorsharp teeth.   Alien Monster

Chaos Aberration

Large aberration, chaotic evil
Armor Class: 18
Hit Points: 164
Speed: 40ft Swim: 50ft


20 +5


14 +2


18 +4


15 +2


10 +0


9 -1

Damage Resistances: acid, cold, fire, poison
Condition Immunities: charmed, paralysed, poisoned
Senses: 120ft truesight,
Languages: Understands many languages but can't speak
Challenge Rating: 10

Magic Resistance   The Chaos Aberration has advantage on saving throws against spells and other magical effects.   Magic Weapons   The Chaos Aberration's weapon attacks are magical.   Regeneration   The Chaos Aberration regains 5 hitpoints at the start of its turn if it has at least 1 hitpoint.   Swamp Adept   The Chaos Aberration is not affected by difficult terrain while in a swamp.


Multiattack The Chaos Aberration makes three attacks: two with its tentacles and one with its bite. If a creature is grappled it can use Mind Terror once.   Tentacle. Melee Weapon Attack:+9, Reach 15ft, one target Hit: 12 (2d6+5) bludgeoning damage plus 7 (2d6) poison damage. The target is grappled (escape DC 19) if it is a large or smaller creature and it has not have two other creatures grappled.   Bite. Melee Weapon Attack:+9, Reach 5ft, one target Hit: 9 (1d8+5) piercing damage plus 7 (2d6) poison damage.   Mind Terror. The Chaos Aberration releases a poison that affects the mind of the grappled creature. When using a tentacle attack it has advantage on the roll and deals an additional 4 (1d8) psychic damage.

  If none of the PCs has noticed the creature it gets a surprise round on the characters. The creature will attack the group but will retreat once it has received over 50 damage. After the fight the group can easily track the creature to its lair.  
The strange creature retreats deeper into the swamp knocking down several trees in the process. Following it to its lair will not be difficult. But seeing the havoc it caused here can there still be survivors?

Hidden Lab


Killing blow

  Following the trail of the creature eventually causes the PCs to stumble upon a rock formation with a cavern. The creature itself has hidden itself inside in an attempt to surprise the group again. It has placed itself at the ceiling of the metallic ruin inside the cavern and will attempt to drop itself on unsuspecting PCs. The creature can, however, be noticed with a successful DC 15 perception test.   Once the players kill the creature they are free to look around in its lair. It becomes clear soon enough that this was not made by the creature and the metallic walls and architecture suggest this could be the work of some unknown advanced civilization. If this oneshot is done apart from another campaign the ruins would suggest it belongs to the Prime Asmer.  
Swamp Research Facility

Research Facility

  Read the following upon inspecting the chamber:  
The place you all find yourself in is unlike anything you have seen before. The walls are made from a sort of metal and although dirty after years of neglect it still looks as hard and sturdy as ever. Whoever made this chamber must have belonged to a quite advanced civilization.   Once you look further around in the room you notice several large tanks filled with a fluid and other strange creatures floating inside. The ones in the room look more plant like than the one you just fought. One of the larger glass tanks seems to have been broken with its fluid spilled all over the ground. At the far end of the room is a large window which gives a view on a gigantic room behind it filled to the brim with glass tanks. All of them filled with strange looking creatures.   Another thing that is pretty noticeable is the large amount of machinery. Especially the large machines at the side of the room are awespiring as lightning can be seen originating from it.
  Further investigation quickly sheds some light on what happened to the caravans as the bodies of several people and horses are found around the room. Investigating the alien creature that the PCs fought reveals the following with a succesful DC 13 Nature check.  
After thoroughly examining the creature you are certain that this creature is not from this world. You are, however, not certain if it was created by magic or not but you notice very cleary that it is affected by some special form of Chaos Corruption.


  If a PC goes to the far end of the room they will notice several panels with text written in Celestial. A PC who can read this can quickly find out that by pressing some buttons they can release the creatures in the room or in the large one beneath it. The tanks can be opened one by one but also all at once.   If any of the tanks is opened a security system kicks in releasing 2 fighting machines to eliminate threats. They come from a small tube near the south part of the room before the security system, mostly likely due to its age, stops working. Nonetheless the machines will start attacking any released creature or other creature standing in its way.   Security Bot

Security Bot

Medium construct, any
Armor Class: 17
Hit Points: 65
Speed: 30ft Hover: 40ft Swim: 30ft


19 +4


16 +3


10 +0


7 -2


13 +1


6 -2

Damage Immunities: Fire, poison, psychic
Condition Immunities: charmed, frightened, paralyzed, exhaustion, poisoned, petrified
Senses: Truesight 60ft
Challenge Rating: 6

Fire Purge   The security bot expels fire from its body to kill any contamination. Any creature that begins its turn within 5 feet of the security bot must make a DC 15 Dexterity saving throw and takes 22 (5d8) fire damage on a failed save, or half as much if successful.    


Multiattack The Security bot makes two attacks with its blades.   Blade. Melee Weapon Attack:+7, Reach 10ft, one target Hit: 14 (3d6+4) slashing damage.




Plant Creatures

  The actions the group take in the hidden lab can actually have a big impact on the world. Releasing any of the plant creatures in the first room does not cause any issues immediately since they are not violent at all. They are a sort of mutated Mizarin Nightlights. If the group would fight choose to fight them use the Lightwalker stats.   Lightwalker


Medium plant, neutral
Armor Class: 14
Hit Points: 75 (10d8+30) 10d8+3
Speed: 30ft Climb: 29ft


16 +3


12 +1


16 +3


11 +0


12 +1


5 -3

Saving Throws: strength +5
Damage Resistances: bludgeoning, piercing
Damage Immunities: psychic
Condition Immunities: blinded, charmed, poisoned, frightened
Senses: truesight 40ft, passive perception 11
Languages: lighttalk, telepathy
Challenge Rating: 4

Treemeld: The Lightwalker is able to meld into a nearby Mizarin Nightlight by using its movement. While merged with the tree, the Lightwalker can’t see what occurs outside it, and any Wisdom (Perception) checks it makes to hear sounds outside it are made with disadvantage. The Lightwalker is not able to use actions while melded.


Multiattack: The Lightwalker can make two attacks with its vines. If a target is grappled he can replace the attack with the Mind Constrict attack.   Vine: Melee Weapon Attack: +5 to hit, reach 10 ft., one target. Hit: 7 (1d8 + 3) bludgeoning damage. If the attack hits the target is also grappled (escape DC 13). No more than 2 creatures can be grappled at the same time.   Mind Constrict: The Lightwalker attacks a creature grappled by one of its vines. This attack automatically succeeds. The target takes 7(1d8+3) bludgeoning damage and must make a Wisdom saving throw (DC 14) or take an extra 4(1d8) psychic damage and is paralyzed until its next turn as a voices overwhelm the target's mind.   Psychic Light: Every creature in a 15 ft radius from the Lightwalker must make a Wisdom saving throw (DC 14). On a fail the target takes 16(3d8 )psychic damage and is blinded until the end of its next turn, on a succesful save the target only takes half that damage and is not blinded.

  There are however issues if they are not killed in the near future as they are actually an extremely invasive plant due to their mutations. If left unchecked they will be able to grow all over the Endra Swamps within a few years. This will most certainly cause issues for any communities living close to the swamp.  

Other Creatures

  Within the large chamber below there are a gigantic amount of strange creatures. If released they can cause some immediate issues for the ecosystem. Although many of them are not very violent, the mutations cause them to reproduce quickly. This can cause all manners of strange creature to spread across the world in a relative short time.  

Exploring the lab

  By spending more time exploring the lab it becomes clear that this was a place for researching or perhaps creating strange creatures. The lower room is not easily accessible from here. By using the small tube from which the machines entered though, PC's can technically explore the lab further. This would reveal a large dungeon with lots of additional enemies and secrets.   Another thing the PC's can discover with a successful DC 16 Intelligence check is that the lightning producing machines are actually a powersource. With a second DC 18 Intelligence check one of these power sources (Celestial Key) can actually be removed. This will, however, cause the base to stop working the next day causing all unreleased creatures to die.  
After searching the room the group finds out that most goods that were being transported are destroyed. But still from the bodies of the dead travellers about 350 GP can be taken.

Adventure Summary

This oneshot is meant to be used with 5e and is designed for a party of 5 of level 7.   This oneshot can actually be added into any campaign as long as the group is travelling through a swamp. However, if it is run as a oneshot the group is sent to the swamp to investigate the recent disappearances of many travelling merchants.   Once they arrive at the swamp they will find an abandoned caravan with signs of violence nearby. Eventually this will lead them deeper into the swamps where they will find a strange and ancient ruins. What secrets await them there?  
This oneshot could later easily be expanded into a longer story as the ruins pose many questions. It can be a start for exploring a vast laboratory or perhaps a reason for many strange alien creatures to appear arround the world.

Adventure Background


The Vanguard

Vanguard Soldiers by Kefkejaco with Heroforge
  The Vanguard is an organisation dedicated to the protection of humanoids along the eastern part of Farlis.The Vanguard was originally formed in the Middle Era when the countries were smaller and did not have sufficient armies to hold off against monsters or other threats to civilization.  
The Vanguard
Organization | Dec 30, 2020

Endra Swamps

by Kefkejaco with inkarnate
  The Endra Swamps are an area in the most western part of Terios. They were formed by the various small rivers flowing from the hills and mountains lying to the south. At the northern edge of the swamps the water combines into a larger river that eventually flows into the Oner river. The area was for a long time not deemed very important besides for the gathering of peat. However, in recent years Sea and Leaf Crystals were found in the area which might make it an important region in the years to come.  

Chaos Corruption

  Chaos corruption is the one of the most feared things in the world of Niorath. No one is spared from it, no plant, no creature and not even the very soil remains unaffected. Once the corruption has run its course it is sometimes even impossible to see what a creature was before it. These mutations can have all sorts of effects and it is best to not attempt to challenge an affected creature unless one is well prepared.   Most of the corruption starts from the use of forbidden Chaos Magic. The bad part is that the effects of this use can remain in an area for ages without showing any decline.  
Chaos Corruption
Condition | May 21, 2022

Prime Asmer

Indovir by Endless Space 2
  The Asmer are seen the Gods and angels of Niorath. They maintained a global civilization until a cataclysmic even known as Magicfall after which they ascended to the Divine Realms. Some are, however, believed to still be on Niorath.   The ruins of their civilization can be found throughout the world but can be hard to find. Not that many people are therefore even really aware of what an Asmer ruin would look like. The more educated people of the world, however, know that they used strange but advanced building materials and had a technology level far ahead of current world.

Prime Asmer
Species | Dec 23, 2021


  The seeds of the Mizarin Nightlight, the Lightwalkers, consist of a series of vines and leaves interwined with each other. Among this mass of vines several light emitting globes can be found with one of the globes at the very top of the Lightwalker, which according to scientists functions as the head. They are able to extend these vines to manipulate the environment around them and move. As a defense mechanism they use these vines to strangle their attackers. Sometimes they even emit bright flashes from their globes which blinds their targets for a short time. Survivors of their attacks have mentioned that they heard voices inside their head while being attack by a Lightwalker.  
Mizarin Nightlight
Species | Apr 26, 2022

Cover image: Endra Swamps by James de Mers on Pixabay


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19 Apr, 2022 23:17

Looks fantastic!!!

Here is my River Challenge Darkwater River! Come vist my world Pangorio for exciting tales, world lore, and RPG adventures ! Hypnosium is my new world I will be trying to fill for Summer Camp ... perhaps even sooner if the muse sttrikes.
25 Apr, 2022 08:21

Thanks! ^^

Feel free to check out my River challenge article and my Secrets in the swamp Adventure article if you want to see what I am up to!
27 Apr, 2022 18:32

Wow, this article looks and reads wonderfully! It gives the players plenty of options, and their decisions have a lasting impact on the world too. :D

30 Apr, 2022 17:37

Very well written and formatted, easy to pick up and run, and an intriguing plot that can stand alone but works even better as a hook for further adventures. The maps and images are absolutely gorgeous. I am a little divided on not having a truly opposing party save for the monsters.... on the other hand, it is unexpected and with your setup, certainly possible. I'd be tempted to add one other scene - make the dungeon a little deeper, or have another encounter. What do you think? It would be very interesting to hear if you run this some time down the road!

If you have some time, I would much appreciate your feedback on my entry for Adventure April: Carbon Copy Paradise
30 Apr, 2022 21:24

Thank you for the kind words! Yes I wanted to expand it as well but I did not want to go too far over the word limit and I am fond of my background sections on the side for giving more info :p The dungeon is much deeper and it could easily be expanded which is perhaps something to do in another plot without word limit! I have run this once already and it ended with the party letting loose a bunch of creatures including the Mizarin Nightlights who will quickly become the main plant in the swamp :p

Feel free to check out my River challenge article and my Secrets in the swamp Adventure article if you want to see what I am up to!
30 Apr, 2022 21:49

I see, countless lives ruined by adventurers like any regular tuesday. :D

If you have some time, I would much appreciate your feedback on my entry for Adventure April: Carbon Copy Paradise