Combining an old-school Arduin module (such as Caliban, The Howling Tower, The Citadel of Thunder, or Death Heart) with the Adventurer Conqueror King System II (ACKS II)

 Combining an old-school Arduin module (such as Caliban, The Howling Tower, The Citadel of Thunder, or Death Heart) with the Adventurer Conqueror King System II (ACKS II) turns a high-lethality, gonzo fantasy playground into a tightly structured economic, military, and sandbox-driven campaign.

Because Arduin leans heavily into dark, science-fantasy, multi-planar weirdness, while ACKS II emphasizes rigorous economic mechanics, domain management, and tactical combat balance, bridging the two requires systematic adjustments.

1. Translating Magic & Mana

• The Arduin Issue: Arduin is famous for massive spell lists, unique magical mechanics, and high-powered magical effects that can easily break standard OSR mathematical baselines.

• The ACKS II Fix: Use ACKS II’s structured magic system as the base, but integrate Arduin’s flavor by treating unique Arduin spells as ancient or forbidden spells researchable via ACKS II's magical research rules. If you use Arduin's Mana point variants, map them onto ACKS II’s spell slot equivalents by converting spell levels into proportional arcane expenditure costs, ensuring players can't spam reality-bending effects without domain-level resource costs.

2. Handling Gonzo Monsters & Lairs

• The Arduin Issue: Arduin modules feature bizarre, hybridized, or ultra-lethal monsters with unusual attacks, cybernetic or mutant traits, and devastating special abilities.

• The ACKS II Fix: Utilize ACKS II’s custom monster creation guidelines alongside the Lairs & Encounters framework.

  • Map Arduin monster HD directly, but assign ACKS II saves and morale ratings.

  • In ACKS II, defeating monsters yields standard XP, but you should also tap into ACKS II’s subsystem where monster parts, hides, and organs hold concrete economic and alchemical value. A bizarre Arduin beast yields rare organ components used for specialized spell research or high-value trade goods.

3. Merging Lethality with ACKS II Domain Play

• The Arduin Issue: Arduin is a notorious "meat-grinder" characterized by instant-death traps, high critical hits, and extreme player vulnerability.

• The ACKS II Fix: ACKS II is built around the transition from low-level dungeon crawling to high-level empire building.

  • The Economic Loop: When players loot an Arduin dungeon, apply ACKS II’s strict gold-for-XP rules. The mind-boggling amounts of treasure typical in Arduin modules will rapidly fund stronghold construction, mercenary contracts, and domain capitalization.

  • The Strategic Toll: High lethality means high turnover. When player characters (or their hired mercenaries) perish to Arduin's brutal traps, it directly impacts the stability and military manpower of their neighboring domains, forcing heirs or newly recruited adventurers to step into ongoing regional conflicts.

4. Integrating Proficiencies & Skills

• ACKS II features a robust proficiency system (e.g., Diplomacy, Bargaining, Mysticism, Engineering).

• Map these directly to navigate Arduin's bizarre sociopolitical encounters. Characters with Elven Bloodlore or high Mysticism gain vital insight when dealing with Arduin's multi-planar factions, weird mutant ecosystems, and ancient techno-magical artifacts, turning what would normally be unfair surprise deaths into puzzles solvable through character build investment.

Converting a classic David A. Hargrave Arduin module (such as Caliban, The Howling Tower, or The Citadel of Thunder) into Adventurer Conqueror King System II (ACKS II) requires anchoring Arduin's chaotic, hyper-lethal science-fantasy within ACKS II's rigorous mathematical baselines and economic loop.

1.Calibrate Dungeon Tier and XP Budget:Perform before converting individual encounters.

Arduin modules rarely stick to a uniform level band, often placing a 14 HD planar horror two doors down from 1 HD goblins. Establish the module's intended ACKS II Dungeon Level (1 through 6+) to determine the baseline Gold-for-XP yield.

• Treasure Normalization: Arduin dungeons often feature absurdly inflated treasure hoards alongside worthless sci-fi junk. Strip out arbitrary inflation and re-anchor major hoards to ACKS II’s Treasure Types based on the total Hit Dice of the guardians, ensuring PCs don't accidentally hit Name Level (Level 9) after clearing three rooms.

• Salvage Value: Assign concrete gold-piece values (in gp) to Arduin's signature weird-tech artifacts, alien alloys, and mutant organs so they plug directly into ACKS II's encumbrance (measured in stone) and specialist alchemy rules.

2.Translate Monster Chassis and Morale:Use the ACKS II Monstrous Manual construction baseline.

Retain the thematic weirdness of Arduin creatures while rebuilding their underlying math so they interact cleanly with ACKS II's attack throws and saving throws.

• Armor Class & Hit Dice: Convert descending Arduin AC to ACKS II ascending AC (19 - Descending AC, capped appropriately for leather/plate/supernatural hide). Keep raw Hit Dice (d8 in ACKS II), adjusting hit points to the standard 4.5 hp per HD average unless the creature is a named boss.

• Attack Throws & Saves: Assign the monster's Attack Throw and Saving Throw progression based strictly on its HD (e.g., a 4 HD creature attacks as a 4th-level Fighter, 7+, and saves as a Fighter of half its HD rounded up).

• Morale Scores: Arduin monsters rarely have standardized morale. Assign ACKS II Morale ratings (-4 to +4): mindless constructs, undead, and berserk mutants get +3 or +4; intelligent mercenaries or scavengers get -1 to +1.

3.Re-engineer Traps and Save-or-Die Hazards:Preserve lethality without bypassing ACKS II proficiencies.

Arduin is infamous for arbitrary instant-death traps (e.g., "step on the purple tile, roll under your Luck or turn to ash"). In ACKS II, lethality should be telegraphed and interact with class abilities.

• Map to ACKS II Saving Throws: Replace Arduin stat checks (Luck, Constitution, or Dexterity rolls) with ACKS II’s five saving throw categories: Petrification & Paralysis, Poison & Death, Blast & Breath, Staffs & Wands, and Spells.

• Damage Scaling: Convert flat instant-death traps into high-dice damage pools scaled by Dungeon Level (e.g., 1d6 per dungeon level) paired with a saving throw for half damage or to avoid secondary conditions like paralysis or limb loss.

• Thief & Proficiency Integration: Assign explicit Find Traps and Remove Traps target numbers (18+ at Level 1, scaling down by level) and allow proficiencies like Engineering, Alertness, or Dungeon Bashing to grant bonuses or clues before a trap triggers.

4.Convert Techno-Magic and Weird Artifacts:Prevent economy and balance breaks.

Arduin blends high sorcery with laser pistols, power armor, and reality-warping runes.

• Limited Charges & Power Cells: Treat sci-fi weaponry (blasters, force-fields) as Magic Items with non-rechargeable charges (e.g., 1d10 + 5 charges). Once depleted, they become high-value curiosities for arcane researchers rather than permanent fixtures that invalidate swords and crossbows.

• Spell Conversion: Map unique Arduin spells onto ACKS II spell levels (1st through 6th) using the ACKS II Revised Rulebook spell creation parameters (range, duration, area of effect, and saving throw modifier).

5.Anchor the Dungeon in a Borderland Hex:Connect the module to ACKS II domain play.

An Arduin dungeon shouldn't exist in a vacuum. Place it within a 6-mile hex on your regional campaign map.

• Factions & Lairs: Identify 2–3 intelligent factions inside the Arduin module and give them external goals—raiding nearby borderland villages, seeking an ancient relic, or vying for control of a subterranean gate.

• Domain Impact: Define what happens if the PCs leave the dungeon half-cleared. Unchecked Arduin monsters spill out into surrounding hexes, lowering local domain morale, disrupting trade routes, and forcing players to deploy mercenaries rather than just a 5-person party.

Practical Conversion Examples

Use these direct translations as templates when adapting specific Arduin stat blocks and hazards into ACKS II:

Arduin Element	Original Arduin Behavior	ACKS II Mechanical Translation
Phraint (Insectoid Warrior)	3+2 HD, AC 3, 2 claw/weapon attacks (1d8), leaps 30 ft, immune to mental control.	AC 6 (16 ascending), HD 3+2 (16 hp), Move 150' (50'), Attacks: 2 (7+ throw, 1d8 dmg), Special: Leap (charge attack deals double damage), Insect Mind (immune to charm/fear), Morale +2, Saves: F2.
Techno-Wraith	6 HD, AC 1, hits only with magic/energy weapons, drains 2 levels on hit, shoots plasma bolt (3d6).	AC 8 (18 ascending), HD 6 (27 hp), Move 120' (40') Fly, Attacks: 1 touch (5+ throw, 1d8 + Energy Drain of 1 level, Save vs. Death negates) OR 1 Plasma Bolt (5+ throw, range 120', 3d6 fire/lightning dmg), Morale +4, Saves: F3.
The Crimson Mist Trap	Room fills with red gas; everyone rolls under CON on 1d20 or lungs dissolve instantly.	Trigger: Pressure plate (Thief Find Traps 14+). Effect: Room fills with caustic vapor in 1 round. All inside must Save vs. Poison & Death or take 4d6 acid damage and suffer a Mortal Wound (roll on the ACKS II Mortal Wounds table at -2).
Arduin Death-Ray Pistol	Fires beam; target rolls 1d20 under DEX or dies instantly; 12 shots.	Magic Weapon (Wand-equivalent): 1d8 + 4 charges. Attack Throw (+2 bonus), range 60'/120'/180'. Deals 3d6 necrotic damage; target must Save vs. Staffs & Wands or be reduced to 0 hp (triggering a standard ACKS II Mortal Wound roll rather than outright un-saveable death).

Handling Critical Hits and Mortal Wounds

Arduin is famous for its brutal critical hit tables, while ACKS II uses the Mortal Wounds and Tampering with Mortality tables when characters drop to 0 hp or lower. Instead of importing Arduin's separate critical hit charts (which can bloat combat tracking), simply apply a -2 to -4 penalty to the ACKS II Mortal Wounds roll whenever a character drops to 0 hp from an Arduin boss, mutant toxin, or weird-tech weapon. This preserves Arduin's infamous amputations, scarring, and grim lethality using native ACKS II rules.

OSR Redo & Recon Converting and expanding Dave J. Browne and Don Turnbull’s classic module U1: The Sinister Secret of Saltmarsh into Adventurer Conqueror King System II (ACKS II)

 Converting and expanding Dave J. Browne and Don Turnbull’s classic module U1: The Sinister Secret of Saltmarsh into Adventurer Conqueror King System II (ACKS II) transforms a straightforward low-level mystery into a rich domain-level, sandbox-ready campaign starter.

In ACKS II, economics, morale, domain revenue, smuggling syndicates, and henchmen management take center stage. Below is a comprehensive guide to running, statting, and expanding The Sinister Secret of Saltmarsh using ACKS II rules.

Part 1: Campaign Setup & ACKS II Domain Integration

In standard ACKS II, 1st-level Adventurers operate at the Heroic Tier (Levels 1–4). Saltmarsh serves as an ideal springboard into the Realm Tier (Levels 5–8) and Domain Tier (Levels 9–14).

1. Saltmarsh Domain Profile

• Settlement Type: Class VI Market Town / Coastal Borderland Settlement

• Dominant Domain Authority: Town Council / Local Magistrate (e.g., Mayor Eda Oweland or Eliander Fireborn).

• Garrison: 1 Leader (Lvl 3 Fighter/Captain), 10 Heavy Infantry (Town Watch), 20 Light Infantry (Militia), 1 Patrol Boat (20 Sailors / Marine Archers).

• Monthly Revenue / Land Value: Saltmarsh generates tax revenue via fishing, salt pans, and coastal shipping. However, a thriving Smuggling Syndicate funnels high-value trade goods off the ledger, leeching potential domain revenue.

2. Economic Context: The Smuggling Enterprise

Smuggling in ACKS II is directly tied to the Trade & Commerce System (Mercantile Trade, Tariffs, and Black Markets):

• Contraband: Brandy, silks, fine tapestries, weapons, and stolen military-grade equipment (weapons meant for Lizardfolk tribes).

• Syndicate Target Revenue: Sanbalet’s operation processes ~2,000 gp worth of contraband monthly, taking a 20% margin (~400 gp profit/month) while avoiding the 10% crown tax on luxury imports.

Part 2: Stat Block Conversions (ACKS II Rules)

In ACKS II, Hit Dice (HD) determine attack bonuses and saving throw target numbers. Moral Checks (2d6) are crucial, especially for bandits, mercenaries, and pirates when their leaders fall or half their force is taken down.

1. Sanbalet (Smuggler Leader)

• Class: Mage Level 3 (or Illusionist / Arcane Specialist)

• Armor Class (AC): 11 (No armor)

• Hit Dice (HD): 3d4 (HP: 11)

• Attacks: Dagger +1 (1d4+1) or Spells

• Save Target Numbers: Fortitude 14+, Reflex 13+, Will 12+

• Morale: 0 (Retreats or surrenders if Sanbalet's guards fall below 50%)

• Spells Prepared: Sleep, Phantasmal Force, Read Magic, Invisibility

• Special: Sanbalet uses illusions to mimic ghosts, creaking floorboards, and flickering spectral lights (the "haunting" of the mansion).

2. Smuggler Goons (Guards / Bandits)

• Class: 1st Level Fighters / Thieves (Normal Human or HD 1-1)

• Armor Class (AC): 13 (Leather + Shield) or 12 (Leather)

• Hit Dice (HD): 1d8 (HP: 5 each)

• Attacks: Shortsword (1d6) or Light Crossbow (1d6, Range 60/120)

• Save: F1 (Fort 13+, Ref 14+, Will 15+)

• Morale: -1 (Check when 50% fall or Sanbalet dies)

3. Ned Noodlehead (Infiltrator / Spy)

• Class: Rogue / Assassin Level 2

• AC: 12 (Unarmored/Leather hidden)

• HD: 2d6 (HP: 8)

• Attacks: Hidden Dagger +2 Backstab (1d4 + Backstab Multiplier)

• Morale: -2 (Will surrender if unmasked and isolated)

• Role: Placed inside the mansion to act as a tied-up victim. His job is to sow discord, ruin party surprise rounds, and betray them during a fight.

4. Coastal Monsters & Hazards

• Giant Weasels / Rot Grubs (Sub-Cellar Hazards):

  • Rot Grubs: 1 HD swarm hazard. Requires a Saving Throw vs. Poison/Disease upon hit; on failure, 1d6 damage per round until burned out with fire or cured with magic.

• Giant Poisionous Snakes (Well): 2 HD (HP: 10), AC 13. Attack: Bite (1d4 + Poison Save vs. Death/Paralysis).

• Skeleton / Zombie Decoys: HD 1 or 2, AC 13, Immunity to Sleep/Charm/Hold. Undead created by an old, long-dead Alchemist whose home Sanbalet co-opted.

Part 3: The Heist & The Ship (The Sea Ghost)

The second half of U1 involves boarding and seizing the smuggling ship, The Sea Ghost. ACKS II features detailed Naval Combat and Ship Rules:

1. The Sea Ghost Ship Stats

• Ship Type: Galley / Coastal Merchantman (Sailing Ship, Small)

• Hull Points (HP): 30–40 HP

• Speed: 90 ft./round (Sailing)

• Crew Capacity: 20 Sailors / Marines

• Armament: 1 Light Catapult / Ballista on the forecastle.

2. Captain Sigurd "Snake-Eyes" & Crew

• Captain Sigurd: Level 4 Fighter (HD 4d8+4, HP 24, AC 15 Chainmail, Longsword 1d8+2). Morale +1.

• Bosun & Mate: Level 2 Fighters (HD 2d8, HP 12, AC 14 Leather/Shield).

• Smuggler Sailors (12): HD 1 (HP 5), AC 12, Cutlasses (1d6), Shortbows (1d6). Morale -1.

• Lizardfolk Passengers (3): HD 2+1 (HP 11), AC 15 (Natural Armor + Shield), Spears (1d6+1), Javelins (1d6). Role: They are buying weapons, not fighting for the smugglers. They will maintain neutrality unless directly attacked.

Part 4: Expanding Saltmarsh for ACKS II (Sandbox & Campaign Hooks)

To maximize ACKS II’s sandbox strength, expand the local node from a single dungeon crawl into a faction war involving domain growth, black markets, and naval conflict.

1. Faction Dynamics & Political Mechanics

In Saltmarsh, three factions struggle for control of the region's market and militia:

1. The Traditionalists (Fishermen & Local Smugglers):

   • Leader: Eda Oweland.

   • Goal: Keep Saltmarsh independent, taxes low, and crown intervention minimal. They tolerate small-scale contraband (brandy/silk) as traditional trade.

2. The Royalists / Loyalist Faction:

   • Leader: Eliander Fireborn (Veteran Captain).

   • Goal: Turn Saltmarsh into a fortified naval base to project military power along the coast and eliminate smuggling.

3. The Marine Syndicate (Sanbalet & Foreign Contacts):

   • Leader: Sanbalet (and behind him, a distant Crime Guild or Pirate Fleet).

   • Goal: Scale up from luxury goods to illegal arms dealing with non-human tribes (Lizardfolk, Sahuagin).

2. Expanding the Loot & Treasure Economy

Standard 1e loot can sometimes overflow early-level campaigns if not adjusted. In ACKS II, Gold equals Experience Points (XP) through investment, domain spending, or carousing:

• Contraband Hoard: Instead of just flat gold, supply trade goods (e.g., 50 Crates of Fine Wine @ 20 gp each, 15 Bolts of Silk @ 50 gp each, 100 Iron Spears @ 3 gp each).

• Cargo Liquidation Rules: Players cannot simply "vendor" 1,000 gp of illegal weapons to the town guard. They must either:

  • Turn it in to the Royalists for Reputation & Service XP (50% value in gold reward from the magistrate).

  • Fence it through the Traditionalists/Black Market using Merchant Class / Vigor/Carousing checks at a risk of local law enforcement intervention.

3. Scaling into U2 (Danger at Dunwater) & U3 (The Final Enemy)

• Lizardfolk Negotiations (U2): The discovery of weapons shipped to the Lizardfolk reveals they are building an alliance against a greater threat: The Sahuagin.

• Naval Warfare & Plunder: If the players seize The Sea Ghost intact, ACKS II allows them to register it as a Privateer Vessel or merchant ship:

  • Monthly Ship Maintenance: ~100 gp/month for crew wages, repairs, and provisions.

  • Trade Routes / Coastal Patrols: Adventurers can run trade routes between Saltmarsh and regional capitals or hunt pirates for bounties paid by the magistrate.

• Domain Expansion (Level 9+): Clearing the surrounding marshlands (Hool Marshes) allows players to build a coastal fort, establish a Class VI market, and tax the salt pans, directly securing the coastline against the Sahuagin invasion force.