B9: Castle Caldwell and Beyond (1985) by Harry Nuckols is unique among classic TSR modules. Rather than presenting a grand, sprawling sandbox or a deeply integrated megadungeon, it is a compilation of five bite-sized, single-session mini-adventures designed for levels 1–3.
While famously critiqued for its surreal "grab-bag" ecosystem (where bandits, goblins, and giant shrews share adjacent rooms without a clear ecological layout), it provides an excellent testing ground for a referee running Adventurer Conqueror King System II (ACKS II). Its modular design allows you to easily drop these locations into your campaign map as local dynamic nodes or domain-level borderland problems.
Here is the comprehensive breakdown for converting and running B9 using the robust mechanics of ACKS II.
1. Setting and Regional Integration (ACKS II Style)
In the original module, the scenarios are mostly loose and disconnected. For ACKS II, you can ground them within a single regional sandbox or a newly claimed Marcher Barony.
The Power Vacuum: Treat the local region as an unmapped Borderland (Wilderness) hex. A local mercantile consortium or a rising Noble (the player characters or an NPC like Clifton) has recently purchased the deeds to the old Caldwell holdings to build a fortified Civilized enclave.
The Five Nodes: Instead of running them back-to-back as an isolated narrative, place them across your regional campaign map:
Castle Caldwell: The actual fortified site chosen for the future casting of a Keep or Fortress.
The Dungeons of Terror: The unmapped vault beneath the castle, masking a ancient, low-level underworld sinkhole.
The Abduction of Princess Sylvia: An active Bandit Hideout/Fortified Camp nestled in a nearby forested hex, threatening trade lines.
The Great Escape: A hostile border outpost belonging to a rival, uncivilized chaotic realm or humanoid faction.
The Sanctuary of Elwyn the Ardent: A small, fortified Chaotic Sanctum or heretical cell run by a rogue Cleric disrupting local divine investment.
2. Converting the Five Mini-Adventures
Adventure 1: The Clearing of Castle Caldwell
The Hook: A wealthy merchant named Clifton has bought the castle but cannot clear the squatters. In ACKS II, this is a textbook Clearing the Wilderness operation for a Level 1 stronghold.
The Dungeon Ecology: The original map features random arrays of goblins, bandits, stirges, and giant rats. To map this to ACKS II conventions, treat the castle as a Lair shared by a splintered, fractious gang. The Bandits and Goblins are currently negotiating a tense truce to split the looting rights of the old estate.
ACKS II Mechanics:
Stirges & Giant Rats: Treat these as wandering hazards or pests nesting in the high towers and collapsed stables (utilizing the Beast Handling or Hygiene proficiencies if characters investigate the filth).
The Reward: Clearing this completely reduces the local wilderness savagery, allowing Clifton (or the PCs) to lay down the initial investments for a regular Market Settlement or Border Fort.
Adventure 2: Dungeons of Terror
The Hook: A trapdoor in the castle floor seals the party inside a small subterranean complex.
The Trapdoor: In ACKS II, standard heavy stone trapdoors require an Open Heavy Doors proficient check or a cumulative strength check. The "magically slamming door" can be attributed to an ancient, localized Mechanical Trap or a lingering Glyph of Warding left by the castle's original builder.
Key Conversions:
The Doppelganger: This is a lethal encounter for 1st-level characters. In ACKS II, ensure the Doppelganger utilizes its Surprise modifiers and mimics a captured retainer or a member of Clifton’s entourage to sow narrative discord rather than just acting as a brute-force combatant.
Green Slime / Yellow Mold: ACKS II handles these as environmental hazards. Green Slime destroys armor instantly unless scraped off or burned. Ensure your players have access to torches, oil, or a character with the Alchemy proficiency to neutralize these threats safely.
Adventure 3: The Abduction of Princess Sylvia
The Hook: A classic rescue mission inside a hidden canyon or woodland hideout. The captors are a mix of bandits, lizardmen, an evil wizard named Oliver of Horn, and a spear-wielding Owlbear.
ACKS II Mechanics:
Oliver of Horn: Convert Oliver into a 3rd-level Mage or Alchemist. Given the absurd nature of the original module's art (showing a bipedal owlbear with a polearm), frame Oliver as a mad specialist who treats the hideout as an improvised alchemy lab. The Owlbear isn't just a monster; it’s his prized, mutated Chimeric Creation.
Lizardmen and Goblins: Frame them as mercenaries hired via the Mercenary Recruitment rules, paid for by Oliver's illicit wealth.
The Rescue: Returning Princess Sylvia intact grants a massive boost to local Noble Reputation and can serve as a narrative justification for a land grant or an introduction to a higher-tier Urban Realm.
Adventure 4: The Great Escape
The Hook: The characters start captured, stripped of their gear, and locked in an enemy military outpost.
ACKS II Mechanics:
The Prison Break: This adventure leans heavily on attribute checks and player ingenuity. Characters with the Thievery proficiency, Escape Artist, or the Contortionism knack shine here.
Scavenged Combat: Because the PCs lack armor and weapons initially, utilize the ACKS II Unarmed Combat and Improvised Weapon rules. Striking an armed guard while unarmored requires leveraging tactical positioning and seeking Surprise values.
The Outpost: Treat the compound as a small Border Garrison holding 10–20 low-level mercenaries or conscripts. Clearing it yields a substantial haul of mundane military equipment (spears, leather armor, shields) perfect for outfitting a player's first unit of Garrison Troops or Peasant Levies.
Adventure 5: The Sanctuary of Elwyn the Ardent
The Hook: The party must infiltrate a fortress to recover a stolen sacred artifact (a mystical Chime of great power) from an evil cleric named Elwyn.
ACKS II Mechanics:
Elwyn the Ardent: Convert Elwyn into a 4th-level Chaotic Priest (or Priestess, keeping the original module's classic twist). Elwyn should have access to Dark Miracles like Blight or Cause Fear.
The Sanctuary: This location functions as a low-level Chaotic Sanctum. It generates a small radius of spiritual corruption, meaning any lawful or neutral Clerics in the party will find the atmosphere oppressive.
The Stolen Relic: Treat the stolen artifact as a low-tier Unusual Magic Item. If returned to the local orthodox church, it provides significant Divine Favor or can be used to offset the costs of establishing a future Sanctuary or Chapel for a divine PC.
3. ACKS II Economy, Treasure, and XP Alignment
Classic Basic D&D modules often have highly inflated coin placement that can warp the tightly regulated ACKS II gold-to-experience pipeline. B9 is a grab-bag of random coin hoards and powerful magic items (such as a Staff of Healing, Wand of Paralyzation, and Ring of Spell Storing).
To keep your campaign economy stable, apply the ACKS II Treasure Hoard Generation rules to adjust the modules as follows:
| Adventure Node | Recommended Treasure Hoard Class (ACKS II) | Adjustments & Placements |
| 1. Castle Caldwell | Hoard Class VI (Shared among room clusters) | Convert loose platinum and gold into trade goods left behind by the merchant Clifton or stolen caravan supplies. |
| 2. Dungeons of Terror | Hoard Class VII (Hidden in Vaults) | Keep the magical traps, but replace excessive coin hoards with ancient, non-functional relics or valuable architectural blueprints. |
| 3. Princess Sylvia’s Rescue | Hoard Class VIII (Oliver's Lab) | Convert a portion of the raw coin into Alchemical Components or valuable reagents worth their weight in gold for spell research. |
| 4. The Great Escape | Hoard Class V (Military Payroll) | Replace random jewelry with a locked strongbox containing the outpost's military payroll, denominated primarily in silver and copper coins. |
| 5. Elwyn's Sanctuary | Hoard Class IX (Temple Treasury) | The high-tier magic items (like the Wand or Staff) should be treated as Relics of the Cult. Elwyn will actively wield them in combat if alerted. |
The XP Scale
Because B9 is meant for characters of levels 1–3, the total XP gained from monsters and adjusted treasures across all five mini-adventures will perfectly push a standard party of 4–6 characters through their first two levels, preparing them to transition smoothly from localized dungeon-delving into early-stage domain management and wilderness exploration.
Yes, absolutely! In fact, B9 is an excellent bridge between ACKS II and Castles & Crusades (C&C), and running a hybrid game or using elements of both systems with this module is remarkably straightforward.
Because both games are direct descendants of classic D&D, they share the same mechanical DNA. However, they approach the tabletop from different angles: C&C provides a streamlined, fast-playing resolution system, while ACKS II provides a deep, simulationist world-building and economy engine.
Here is how you can use B9 to seamlessly blend the two systems, or choose how to leverage the best parts of each for this specific module.
1. The Mechanical Compatibility: Stats and Monsters
Because C&C and ACKS II both derive their math from early editions of the world's most popular RPG, converting monsters on the fly during a B9 session requires almost zero prep.
Hit Dice (HD) and Armor Class (AC): A 2 HD goblin or a 1 HD bandit in B9 translates perfectly to both systems. If you are using C&C's ascending AC, simply convert the module's descending AC (e.g., AC 7 becomes C&C AC 13 / ACKS II AC 2).
The Siege Engine (C&C) meets Proficiencies (ACKS II):
Adventure 4 (The Great Escape) requires characters to break out of prison. In C&C, you will resolve this instantly using the Siege Engine (a Dexterity or Strength attribute check against a Challenge Class, favored by Prime Attributes).
In ACKS II, you would look at specific character Proficiencies (like Thievery or Escape Artist).
The Hybrid Fix: Use C&C’s elegant attribute-based Siege Engine for the moment-to-moment action rolls, but grant a +2 or +4 bonus if a character possesses a relevant ACKS II proficiency.
2. Setting up the Sandbox: ACKS Domains with C&C Rules
The best way to combine them for B9 is to use Castles & Crusades as your primary ruleset for exploration and combat, while using ACKS II to manage the campaign world, economy, and endgame.
Step 1: Mapping B9 into an ACKS II Borderland Hex
Use the ACKS II wilderness rules to place Castle Caldwell on your regional map.
Define the area as a Borderland hex.
The players use C&C rules to delve into the castle and clear out the monsters.
Once cleared, switch to ACKS II mechanics to calculate how much it costs to clear the surrounding wilderness, establish a market, and attract peasant families.
Step 2: The Economy Clash (Gold vs. XP)
This is the one critical area where you must make a design choice:
Castles & Crusades defaults to a modern style where defeating monsters provides the bulk of XP, and gold is just for buying gear.
ACKS II relies heavily on a 1 Gold Piece = 1 XP model to pacing character leveling and fund domain management.
The Recommendation: If playing a hybrid game, use the ACKS II XP-for-Gold system. B9 has a lot of loose treasure. If you use C&C's monster-only XP, your players will level up very slowly in these short dungeons. If you give XP for gold, clearing Castle Caldwell will give them the exact financial war chest they need to hire the C&C equivalent of mercenaries and torchbearers.
3. Class and Magic Conversions for B9
The Spells
B9 features two prominent spellcasters: Oliver of Horn (Adventure 3) and Elwyn the Ardent (Adventure 5).
In C&C: Oliver is a 3rd-level Wizard; Elwyn is a 4th-level Cleric. You can use their standard spell lists straight out of the C&C Players Handbook. C&C's prismatic magic system makes Elwyn's unholy spells feel appropriately dark and dangerous.
In ACKS II: If you want a grittier tone, give Elwyn access to ACKS II Dark Miracles. Instead of a standard Cause Light Wounds, Elwyn can cast a lingering sickness that requires the party to seek out a high-level sanctuary to cure.
The Magic Items
B9 features high-powered items like a Staff of Healing and a Wand of Paralyzation.
C&C Approach: C&C handles these items classically. They have standard charges and work exactly as a veteran player expects.
ACKS II Approach: ACKS II views magic items as rare, volatile commodities. If the players try to sell Elwyn's Staff of Healing to fund their castle renovations, use the ACKS II Magical Commerce rules. Selling a major item requires finding a broker, paying taxes to the local realm, and risking the attention of thieves.
Summary: The Perfect Hybrid Blueprint
If you choose to run B9 using both systems simultaneously, layout your campaign structure like this:
| Game Element | Which System to Use | Why it Works |
| Character Creation | Castles & Crusades | Fast, intuitive, and highly customizable with the archetype system. |
| Dungeon Combat & Traps | Castles & Crusades | The Siege Engine resolves trap detection and attribute checks in seconds without looking up tables. |
| Treasure and Pacing | ACKS II | Keeps gold meaningful. The coin found in Castle Caldwell serves as direct experience and future investment capital. |
| Post-Dungeon Campaign | ACKS II | Once Elwyn is defeated and the Princess is saved, the players use ACKS II to manage their new local reputation and build their own barony. |
