735 Prison of Thorns – Lv-3 Adventure

“May the Prison of Thorns be a bastion of safety and justice. Wrong-doers and criminals should experience the same fear as their victims did”.

Oxenta’s Ruler

Some years ago, the ruler of Oxenta, in a bid to quell rising crime, commissioned the con­struction of a prison imbued with arcane en­chantments. These incantations were meant to serve as a deterrent to would-be criminals, inflict­ing upon them a punishment so dire that even the most hardened offenders would shudder at the thought.

Within the walls of the Prison of Thorns, the bod­ies of inmates and prisoners would sprout thorns, like the gnarled branches of malevolent trees, as part of their sentence and punishment. For those condemned to death, the enchantment grew even more sinister, as jagged spikes erupted from their very bones, tearing through flesh and muscle in a grotesque display of agony.

Unexpected Outcome

Magic is chaos. After some time, the arcane spells, meant to administer justice, instead spiraled out of con­trol. No longer discriminating between the guilty and the innocent, the magic claimed all within its grasp, snuffing the lives of all within the prison indiscriminately.

In the aftermath of this catastrophe, the tortured souls of the deceased, their bodies twisted and contorted by the thorns and spikes that had consumed them, rose from the earth as ghastly revenants. Faced with the dire consequences of their ruler’s ill-conceived endeavor, the city now stands in desperate need of aid.

The prison was shut down and the city locked all the monsters inside. To confront the malevolent spirits that now roam the Prison of Thorns, the call goes out for brave souls, heroes willing to venture into the heart of darkness and vanquish the horrors that dwell within.

Adventure Hooks

Heroes. A group of intrepid adventurers is thus as­sembled, their courage the Oxenta’s last hope against the spectral terrors that infest the accursed prison. They must eliminate all threats within (1,500 gp, 7 XP).

Level 3 Adventure

  • Danger. Risky. Check for a Random Event every 2 crawling rounds and after loud noises (4-in-6 chance).
  • Light. Some areas feature magical braziers that stay ever-burning. The undead within are all dark-adapted.
  • Smells and Sounds. The Prison of Thorns exudes a noxious aroma of decay mingled with the faint rustle of spectral whispers echoing through its twisted corridors.

Thorny Undead

The undead of this dungeon possess the following:

Thorny Grab. (DC 12 DEX) On a fail, 1d4 damage, and the target is grappled. Automatic damage each round until the target frees themselves or the undead is killed.

Death Throes. The undead explodes when it drops to 0 HP. 1d6 damage (DC 12 DEX check) to all creatures (including other undead) standing 5 feet from it.

1 The heroes encounter a ghoul. A giant thorny growth in his thigh. His right hand is impaled there. He still fights to the death.
2 The arcane incantations are chaos. The uncontrollable magic targets one of the heroes at random (DC 13 WIS check). On a fail, a nasty thorn grows from their back, piercing through skin, clothes, and armor (1d6 damage). Only magic can heal this.
3 The magic is still causing cave-ins. The entire dungeon vibrates and debris falls on a random hero (1d8 damage, DC 12 DEX).
4 The characters stumble upon a group of three skeletons. All three attempt a Thorny Grab (see above) on the same target.
5 The heroes meet Kev, a friendly ghast. He was a prison guard. He managed to remain lucid even after the thorny transformation. He promises to help the heroes. But there is a 1-in-6 chance every crawling round that he loses his mind and attacks.
6 The characters find 120 gp inside a leather bag on the floor. Two zombies walk up to them after they take the loot.

 1. Main Landing and Holding Cells

The wooden desks are filled with unfinished notes and papers. Six barred alcoves work as holding cells. Four of them hold a skeleton each. The cells open when the heroes arrive. The middle south cell features a tunnel, a consequence of a recent cave-in. It leads to area 3.

2. Antechamber

A lush, crimson rug stretches from beneath, leading towards and beyond the formidable double doors at the chamber’s end. To the north and south, corridors branch away. The walls themselves are canvases, adorned with detailed frescoes of the city, Oxenta.

Two small tables hold gold vases. They are free for the taking. The pair is worth 45 gp to the right buyer (2 XP).

3. Cavern Network

Since the chaotic magic was released, the dead roam freely, wild magic travels the dungeon, and new passage­ways were discovered. A vast cavern network is connect­ed to the Prison of Thorns. The heroes may find:

  • Fungi. Three mushroomfolk inhabit these caverns. Telepathically, they warn intruders. No torches shall be allowed or tolerated. If the heroes put off their torches (if any), or if they use a lamp to light their path, they may pass unharmed. Otherwise, the ‘shrooms attack!
  • Secret Passage. A perceptive character may notice the brick that must be pushed to slide a section of the wall sideways and reveal a path to area 8 (DC 13 WIS).
  • Dark Tunnels. Stalactites and stalagmites populate the way, their silhouettes like jagged teeth, promising a dangerous descent. Following this path leads to a small moss-ridden cave. Four rot flowers attack anyone who approaches. The tunnels beyond fork into endless paths.

4. North Block

This section of the prison features five holding cells. They are either open or their bars bent outward. Two skeletons and one ghoul, all covered in sharp thorns, stand near their former cells. They attack intruders.

  • Tunnel. One of the consequences of the recent cave-ins is the connection between this area and the arcane chamber (area 9, see map). However, this humid tunnel is home to a swarm of spiders. The insects do not chase enemies outside their nest and flee if reduced to half HP.

5. Twin Cells

These larger cells are locked and closed. Word on the street is that Oxenta’s authorities often punished crimi­nals even further by putting six or even eight individuals together in here for days. One cell is empty. The other contains three skeletons standing still. Their only move­ment is their head turning toward the nearest intruder. One of the skeletons wears a beautiful, shiny, gold ring.

  • Treasure (3 XP). The golden relic is a ring of protec­tion. Its wearer gains a +1 bonus to their AC.

6. Large Cell

This cell is also closed. Five skeletons stare at the in­truders from within. Unlike their neighbors in area 5, they do not remain still, and try a Thorny Grab through the bars if the characters approach. There is a 4-in-6 chance that the door opens from the struggle.

7. Studio

In the prison’s depths, a clandestine studio thrives. Chains and weapons adorn the walls, serving as grim decorations. Here, the prison guards took breaks, wrote journals, and did time-consuming paperwork.

The desk shows unfinished notes. The person doing this suffered the same fate as the inmates and became a monster. The shelf contains books and logs with the Prison of Thorn’s history and prisoner count.

8. Office

This hard-to-reach chamber is an extension of the stu­dio. Two ghouls stare at the furniture as if trying to fig­ure out what it is for. They fight intruders until slain. If the heroes spend 1 crawling round reading the docu­ments in this chamber they learn the following:

  • The list of employees is too long. There must be some money-laundering going on (DC 14 INT).
  • The prison’s magic was paid for with tithes and tax money. The population of Oxenta is not going to be happy to know their gold only satisfies the wishes of their egotistic ruler, and not the people’s.
  • The characters learn the bases of the spells and incantations placed in the arcane chamber (area 9). Mages or priests interacting with the magic de­vices in area 9 gain advantage on their first check.

9. Arcane Chamber

The runes engraved all around this room pulse with dark magic, cursing inmates with thorns that pierce flesh, a horrible, perpetual, painful penance.

The incantations in this chamber are the ones that failed. A mage or priest among the heroes must be attuned to this wild magic (DC 13 spellcasting check). They make this check with advantage if they read the documents in area 8. On a success, they nullify the incantations and dispel them. On a fail, they may try a second time (with­out advantage this time). On a second failure or a fail by 5 or more, the device breaks, and all heroes are affected by Random Event 2, with no save (see table).

10. Cells of Hate

Four zombies are imprisoned here, two in each cell. The sight of living creatures makes them walk forward and realize their cells are open. The zombies attack.


This place should have never existed. But now the heroes know crucial information that may jeopardize the position of Oxenta’s ruler (see area 8). What the charac­ters do with these facts is an adventure for another day…

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