OSR Meditations - Using The classic TSR module C3: The Lost Island of Castanamir by Mike Breault for Adventurer, Conqueror, King II Rpg

 C3: The Lost Island of Castanamir (originally published by TSR for AD&D in 1984) is a non-linear "funhouse" island crawl and planar maze designed by Mike Breault. The module drops player characters (PCs) into the mysterious, magically unstable island retreat of Castanamir the Mad, an archmage who vanished decades ago.

Below is an adaptation of The Lost Island of Castanamir formatted for Adventurer Conqueror King System II (ACKS II), tailored for 1st–4th level characters.

1. Module Overview & ACKS II Tone

In ACKS II, Castanamir’s retreat functions as a mythic underworld/planar nexus:

• The Dilemma: The island itself is surrounded by magical fog and dimensional distortion. Once the PCs enter the central residence (the Grotto and the Sanctum), room connections shift, teleporters rearrange paths, and standard mapping is unreliable.

• Goal: Escape the island, claim Castanamir’s lost artifacts, and navigate the competing factions trapped inside.

• XP Alignment: ACKS II places high value on gold and treasures (1 GP = 1 XP). The module contains high-value magical items, spellbooks, and trade goods, making careful looting essential for low-level leveling.

2. Converting Key Mechanics to ACKS II

Traps & Searching

• Searching: Finding secret doors, concealed panels, or hidden teleporters follows standard ACKS II searching rules (Proficiency Throw vs. Target Value 18+, or 14+ for Elves/Dwarves/Thieves using Find Traps / Detect Secret Doors).

• Dimensional Disorientation: Mapping the interior requires a Navigation or Mapping Proficiency Check (or INT check at -4) after traversing teleporters. Failure causes disorientation, imposing a -1 penalty to surprise rolls inside the complex.

Wandering Encounters (1 turn in 3)

Roll 1d6 on a result of 1. Roll 1d8 on the table below:

d8	Encounter	ACKS II Stat Block Summary
1	2d4 Giant Rats	HD 1/2, AC 12, Bite (1d3 + disease), MV 120', ML -1
2	1d4 Hobgoblins	HD 1+1, AC 14 (Chain), Weapon (1d8), MV 90', ML 0
3	1d2 Gargoyles	HD 4, AC 16, 2 Claws/Bite/Gore (1d4/1d4/1d6/1d4), Immune to non-magical weapons, MV 90'/150' fly, ML +2
4	1 Iron Cobra (Automaton)	HD 3, AC 16, Bite (1d3 + Poison: Saving Throw vs. Poison or take 2d6 damage), MV 120', ML +4
5	1d3 Shadows	HD 2+2, AC 13, Touch (1d4 + 1 Strength Drain), Immune to sleep/charm, MV 90', ML +2
6	1 Gelatinous Cube	HD 4, AC 12, Touch (2d4 + Paralysis 2d4 turns), Immune to cold/lightning, MV 60', ML +4
7	Castanamir’s Trapped Apprentice (Gorg) & 1d3 Skeleton Bodyguards	Gorg: Level 2 Mage (HD 2, AC 10, Magic Missile, Sleep); Skeletons: HD 1, AC 13, Claws (1d6), ML +4
8	1 Air Elemental (Lesser Bound)	HD 4, AC 16, Slam (1d8), +1 or better weapon to hit, MV 360' fly, ML +2

3. Major Dungeon Regions & ACKS II Encounter Design

Region 1: The Island Exterior & Landing

The PCs arrive via shipwreck or mysterious magical drift onto a fog-wrapped, rocky isle.

• Key Encounter: The Stone Statues (Island Coast)

  • Setup: Animated statues guarding the entry paths.

  • ACKS II Stats (Living Statues - Rock): HD 3, AC 15, 2 Strikes (1d6 each), ML +4. Hard skin grants damage resistance (takes 1 less point of damage per die from mundane weapons).

Region 2: The Grotto & Surface Level

A series of carved marble chambers disguised as a natural cave system. Contains the entry chambers and service quarters for Castanamir’s former staff.

• The Mirror Room:

  • Hazard: Looking into the main mirror requires a Saving Throw vs. Spells. Failure causes the PC's reflection to step out as an Exact Shadow Duplicate (HD equal to character, AC/Attacks identical, no spell slots).

• The Library:

  • Loot: Scrolls containing ACKS II arcane spells (Detect Magic, Read Languages, Invisibility, Fireball [1 charge left]), plus trade books worth 800 GP to a sage.

  • Trap: Glyph of Wardening on the primary spellbook. Triggers an explosion: 2d6 fire damage in a 10' radius (Saving Throw vs. Blast for half).

Region 3: The Teleporter Network (The Maze)

The central gimmick of C3 is a network of doorless rooms linked by invisible teleporter pads.

• ACKS II Dungeon Flow:

  • Instead of traditional corridors, rooms feature lettered portal pads (Pad A to Pad B).

  • Reversing direction does not take the party back to the room they came from unless specified.

  • Thief / Mage Utility: Detect Magic reveals active teleportation circles; Find Traps identifies pressure plates that cycle portal destinations.

Region 4: The Inner Sanctum & Laboratory

The deepest sub-level, housing Castanamir’s experiments, bound extraplanar beings, and his primary vault.

• Encounter: The Bound Dao / Djinn Chambers

  • Castanamir trapped extraplanar beings to power the sanctuary's wards.

  • ACKS II NPC Interactions: High reaction check potential (2d6 Reaction Roll). The extraplanar being offers a secret exit or treasure location in exchange for being freed from its warding circle. Breaking the circle requires a Knock spell, a successful Dispel Magic, or destroying three anchor runes (AC 14, 15 HP each).

• Encounter: Castanamir’s Laboratory & Avatar

  • While Castanamir himself is absent or transcended, a Construct / Animated Avatar guards the final door.

  • Avatar of Castanamir (Iron Automaton Variant): HD 5, AC 17, 2 Fists (1d8+2), Casts Lightning Bolt (4d6, once per encounter), ML +4.

4. Key Treasure & Rewards (ACKS II Economy)

To align with ACKS II progression for levels 1–4, total available loot is calibrated to approximately 12,000–15,000 GP value across the entire module (divided among a standard party of 4 to 6 adventurers, granting enough XP to reach levels 3–4).

• The Ring of the Planar Key: Allows the wearer to lock a portal pad in place for 1d4 turns. (Value: 3,000 GP / XP).

• Castanamir’s Spellbook: Contains 1st–3rd level Mage spells. High resale value (4,000 GP) to an Arcane Guild, or invaluable for a player Mage's library.

• Alchemical Stash: 6 Potions (Healing, Invisibility, Levitation, Cure Poison, Heroism).

• Planar Gemstones: 12 rare planar-infused diamonds (500 GP value each).

5. Judge's Tips for Running C3 in ACKS II

1. Track Torch & Supply Duration Strictly: Because the maze teleporters can loop players endlessly, tracking turns, light sources, and rations creates natural survival tension essential to early-level ACKS II play.

2. Encourage Mercenary/Henchman Recruitment: ACKS II places strong emphasis on henchmen. Trapped NPCs inside the module (such as lost sailors or rival adventuring parties) can be recruited using the standard Recruitment & Loyalty rules to bolster a fragile Level 1–2 party.

3. Morale Checks Are Essential: Monsters in ACKS II rarely fight to the death. Use Morale Checks (2d6 + ML) when monsters hit half health or when their leader falls. Intelligent creatures like Hobgoblins or trapped adventurers will readily negotiate or surrender if outmatched.