Building The Mystery of Maeralon's Tower with ChatGPT

Adventure Seeding

In my last post in this series, I said I wanted to do a hybrid game using a cool set piece from my terrain collection. That was the seed for the adventure. It didn't take long for me to decide I wanted to use Dwarven Forge's Watchtower because it was a cool piece I had never used before (and it gave me motivation to get it painted). 

Since I knew I wanted to use the Watchtower, I used that as a building block. I decided to make it a wizard tower in the Field Ward, and that led to involving the Watchful Order of Magists and Protectors since it was a wizard's tower. That also meant I could use Barnabus Blastwind as the quest giver and have it feel like a big faction quest. I decided I would use the Arcane Ballista atop the tower as the threat to passersby that required prompt action from the adventurers. Then I went through and picked out some monsters (preferably constructs) to populate the tower. I summarized all that in this outline:

• Call to Action
  • Barnabis Blastwind tells the party the Watchful Order of Magists and Protectors have an emergency: a wizard tower in the Field Ward is attacking passersby.
  • He wants the party to enter the tower and disable the arcane ballista on top, find out what happened to the wizard that lived there.
  • He has already notified the wizard’s next of kin, who is studying with the Harpells in Longsaddle, so won’t be here for a few days.
  • If the party can deal with the threat, he will give them 500 gp.
• Approaching the Tower
  • The animated Ballista atop the tower fires at the party as they approach. It is encased in a prismatic sphere it can fire out of but hard for party to fire into. The party has to evade fire and get to the front door, which is locked. DC 14 sleight of hand with thieves' tools to unlock.
  • Anywhere within 50 feet of the tower is a wild magic zone. Anytime someone casts a spell a wild magic surge occurs.
• Inside the tower
  • On level 1, a Living burning hands attacks the party.
  • On level 2, 3 Stone Cursed attack the party.
  • On level 3, the party finds the dead body of the wizard with a Clockwork Iron Cobra looming over it. There is also a bed and a bookshelf n the room, and a chest that turns out to be a mimic.
  • On the top of the tower is the Animated Ballista and an orb on a pedestal. Taking the Study action to make a DC 16 Intelligence (Arcana) will turn off the pedestal, which ends the prismatic sphere, wild magic zone, and disables any remaining enemies except the mimic.
• Rewards
  • Barnabis Blastwind gives the party 500 gp and they gain 3 renown with the Watchful Order of Magists and Protectors.
  • Eventually, the son shows up, and if the characters looted nothing from the tower, he gives them each a potion of healing, a wizard spell scroll of up to third level with the supplies to scribe it, and a +1 weapon.

Getting Help from ChatGPT

Next, I have a custom GPT on chatgpt.com I have created called Volo. GPTs let you set additional specific context (via uploaded PDFs) for the LLM to use and prioritize when giving answers. I've found this works very well with Dungeons and Dragons as it focuses the LLM and leads to fewer hallucinations and more relevant responses overall. This LLM has access to all of the published Waterdeep source books plus a few supplements I purchased on DM's Guild. 

So I took the outline above and fed it into my GPT with this prompt: "Can you take this adventure outline and add details to it? Things like what are on the levels of the wizards tower, who the wizard and his son are, some details about the magic weapon, etc?" Below is the unedited initial result provided by ChatGPT. I'll provide an assessment of how what it did well and what it did poorly beyond the adventure. For reference, here is a link to my prior post with my finalized version of the adventure. 

The Mystery of Maeralon's Tower, ChatGPT version

Adventure Title: The Mystery of Maeralon's Tower

Call to Action

Barnabus Blastwind of the Watchful Order of Magists and Protectors approaches the party with an urgent request. The Watchful Order has lost contact with Maeralon Silvercord, a reclusive yet respected wizard living in the Field Ward. His tower has activated defenses and launched attacks on passerby, and no one has been able to approach safely. Barnabus offers the party 500 gp to investigate, disable the defensive magic, and determine what happened to Maeralon.

Background: Maeralon Silvercord was a known enchanter and artificer, especially interested in defensive magics. His last known project involved binding an otherworldly sentience to a magical item. His son Arastin Silvercord is a budding wizard studying with the Harpells in Longsaddle and won’t arrive in Waterdeep for several days.

Approaching the Tower

• The Arcane Ballista: This enchanted ballista at the top of the tower fires bolts that contain explosive magical energy. Encased in a Prismatic Sphere, it can shoot bolts out but is difficult to damage in return.
• Wild Magic Zone: A 50-foot radius around the tower is suffused with unstable magic. Spellcasting here triggers Wild Magic effects, with a variety of outcomes inspired by the Magical Chaos Table from FRE3​. Effects could range from harmless illusions to unexpected surges of elemental energy. This chaos may hint that Maeralon’s last project has broken free from control.
• Entry Challenge: The tower’s door is reinforced with an arcane lock, requiring a DC 14 sleight-of-hand check to unlock. Failure by 5 or more results in a small shock, dealing 1d4 lightning damage.

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Inside the Tower

The tower has four floors, each serving a unique purpose in Maeralon’s studies.

Level 1: Entrance and Reception

Upon entering, the party is greeted by a Living Burning Hands spell—a defensive conjuration designed to dissuade intruders. The room appears to be a study, scattered with papers and books on enchantments and defensive magics.

• Clues: Among the papers are notes about "binding sentient power" and a half-finished rune sketch that suggests a project to animate or empower an object with a fragment of consciousness.

Level 2: Library and Workshop

This level contains shelves of books on magical theory, elemental magic, and lore from various realms. At the center of the room, three Stone Cursed statues stand, which will animate and attack when the party arrives. These statues were crafted from Maeralon's own failed attempts to animate his tower’s defenses.

• Workshop Details: The workshop has an alchemist’s lab and a magic circle etched into the floor, surrounded by candle stubs and scorched runes. Here, Maeralon had been testing containment spells, hinting that he might have bound an entity to one of his creations.

Level 3: Maeralon’s Quarters

The party finds Maeralon’s body on the floor, his face frozen in shock. A Clockwork Iron Cobra, his guardian construct, stands menacingly nearby, and a Mimic disguised as a chest lurks in the corner.

• Character Insight: Maeralon was experimenting with soul fragments, attempting to infuse one into a weapon. Among his belongings are letters from Arastin, suggesting his son was concerned about his father’s deepening obsession with “infinite defense.”

• Clues and Lore: On his desk is a half-finished manuscript on binding spirits. His final notes reveal he was trying to enchant a weapon with sentient awareness, referencing an artifact called The Watcher’s Edge.

Level 4: Roof and Control Room

The top of the tower houses the Animated Ballista and an orb on a pedestal. The orb functions as the control core, projecting a Prismatic Sphere around the ballista and maintaining the wild magic zone around the tower. If the party makes a DC 16 Intelligence (Arcana) check and succeeds, they can disable the control orb, deactivating the sphere, the wild magic, and neutralizing remaining constructs (except for the mimic).

• Orb's Background: It contains a piece of Maeralon's own will, stored as a last defense mechanism.

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Key NPCs

• Maeralon Silvercord: A once-reclusive wizard known for his defensive enchantments, Maeralon was driven by the idea of a perfect defense. His experiment with sentience, meant to infuse his creations with awareness, ultimately led to his demise when his magic went awry.

• Arastin Silvercord: Maeralon’s son, a young wizard studying under the Harpells in Longsaddle. Unlike his father, Arastin is more practical, with an interest in protective wards. If the party treats his father’s possessions with respect, Arastin rewards them generously.

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Rewards

• Barnabus’s Payment: The 500 gp reward and 3 renown with the Watchful Order.

• Arastin’s Gratitude: If the party leaves the tower’s items untouched, Arastin provides each member with a Potion of Healing, a Wizard’s Spell Scroll of up to third level, and a +1 Weapon with a unique enchantment.

• The Watcher’s Edge (Optional Magic Weapon): This sentient weapon was Maeralon’s final project. The Watcher’s Edge is a longsword (or other weapon of choice) that grants +1 to attack and damage rolls. As a sentient weapon, it provides its wielder with advantage on Perception checks and has a limited form of communication, capable of sending warnings to its bearer about nearby dangers. However, it also has an overly cautious personality, sometimes alerting the wielder to harmless things.

So How Is It?

The Good

• I was able to run a fun session using the adventure it generated. This is huge for any DM trying to quickly cook something up on short notice. Thirty minutes of prep to put together the main inspirations, and then ChatGPT can do the leg work of filling out the details. 
• Annnnnnnd I am struggling for a second bullet. But that first one, in my opinion, is huge for everyday DMs just trying to make it through the next session. 
• Speaking of, there are lots of avenues to help the AI do better. Giving it the full text log of the campaign recaps and a WotC style guide alone would probably be a big help (and I think I will do so next time I use ChatGPT to prep). 

The Bad

• The most glaring issue is the power it gives the magic item - advantage on all Wisdom (perception) checks. If a new DM just blindly followed the output it could mildly break their game if there is a high perception character - the party will spot every ambush, secret door, etc. Never (or rarely) failing takes a lot of the joy out of the game in my opinion. I changed that to advantage on one initiative check per Long Rest. That's useful and generates an interesting player choice (is this the encounter to use it?).
• Some of the turns of phrase are just awkward. "Perfect Defense" is a good example. It's not believable that a real person would talk like that. That said, it leads down a path of a relatable stereotype (a person growing more paranoid as they age) that's useful and relatable if maybe a bit cringe. 
• ChatGPT has no clue about the WotC style guide. I will try to give it the style guide ahead of time next time to see if it does better - I think it will. 
• While it is a great tool to flesh out an adventure, if your goal is publishing, I'd call it a minor improvement. It came up with some proper names for me and spurred some ideas about how to flesh out the adventure, but I would guess I rewrote 70% of the adventure to make it something I would publish on my niche blog. I'd say it saved me 1-2 hours of work. Not that much in the grand scheme of things for publishing something, but quite a bit if you are prepping a weekly game and it will never go beyond your home group.