Converting David A. Hargrave’s legendary 1978 supplement, The Arduin Grimoire Vol. II: Welcome to Skull Tower, into ACKS II (Adventurer Conqueror King System II) provides your campaign with a central hub for planar travel and dungeon-crawling. This blog post picks right up from Integrating Adventurer Conqueror King System II (ACKS II) with the legendary, chaotic, and maximum-gonzo DNA of Dave Hargrave's Arduin Grimoires - Random Fey & Fairy Encounters
In the original texts, Skull Tower isn't just a single mega-dungeon layout—it is the quintessential planar multi-level megastructure, a nexus point of the multiverse where high-tech space marines and ancient liches rub shoulders.
Converting it involves structuring its multi-dimensional economy, handling its lethal traps using ACKS II proficiencies, and managing it as a high-level domain.
1. Establishing Skull Tower as a Class I Market Nexus
In ACKS II, a Class I Market City represents a massive metropolis with access to almost every conceivable luxury, resource, and mercenary pool. Skull Tower functions as a vertical, highly militarized Class I Market City nestled in the wilderness.
Planar Infrastructure: Because its gates pull from infinite realities, ignore standard regional population density math when stocking its markets. Assume a virtual population of 100,000+ equivalent consumers moving through its gates.
The Market Modifier: Apply a permanent +2 bonus to all Market Availability rolls for Technic Salvage, Alien Slaves, Magic Items, and Rare Monster Parts. Conversely, standard agricultural goods (grain, livestock) face a 300% markup due to the barren nature of the surrounding terrain.
2. Converting the Dungeon Ecology & Levels
Skull Tower is notoriously high-lethality. When converting the legendary encounter tables and floor layouts into the strict mathematical framework of ACKS II, map them into precise Dungeon Tiers:
Tier Translation Matrix
| Skull Tower Level | ACKS II Dungeon Level Equivalent | Typical Factions / Denizens | Wandering Monster Metric |
| Upper Spires (1–3) | Level 4–6 (Challenging) | Phraint Hives, Disgraced Mages, Rogue Technos | Roll 1d6 every 2 turns; 1 indicates an encounter. |
| The Nexus Plazas (4–6) | Level 7–9 (Dangerous) | Interstellar Pirates, Deodand Slavers, Demons | Roll 1d6 every turn; 1 indicates an encounter. Heavy traffic. |
| The Depths & Vaults (7+) | Level 10+ (Legendary) | Chronomancers, Cosmic Horrors, Dead Gods | Checks include exposure to Poison/Radiation hazards. |
The "Room of Respite" Conversion
Skull Tower famously features single, isolated safe-rooms on every floor where the laws of the dungeon are suspended.
ACKS II Integration: Treat these as localized Sanctuary Zones. Characters resting inside a Room of Respite heal at double the normal rate and are completely immune to random encounter checks. However, characters cannot remain in a single Room of Respite for more than 24 hours without triggering a structural reality-shift that teleports them randomly into the wilderness.
3. Trap and Hazard System Translation
Hargrave’s original modules are packed with instantaneous "save-or-die" style traps, radiation pools, and acid pits. ACKS II formalizes these into structured saving throws and proficiency checks.
The Technology Trap: If a trap features advanced wiring, lasers, or mechanical sensors, a standard Thief's Find/Remove Traps skill suffers a -4 penalty unless they possess the Ancient Lore (Technology) proficiency or are of the Techno class.
Radiation Pools: Replace Arduinian "Radiation Points" directly with the ACKS II Poison/Radiation Saving Throw.
Mild Exposure: Failure inflicts 1d6 temporary Constitution damage.
Severe/Nuclear Exposure: Failure causes instant systemic necrosis (treat as a Death result on the mortal wounds table if not treated within 1 turn via a Sub-Dermal Coagulation Matrix or high-level magic).
4. Late-Game Domain Play: Capturing or Governing the Tower
If your party reaches levels 9–14 (Conqueror to King phase) and successfully cleanses or claims a portion of Skull Tower, the domain-level mechanics of ACKS II shift into hyper-gear.
Domain Revenue: The World-Gate Tariff
Instead of calculating land income based on peasant farming families (which requires vast agricultural acreage), a domain centered on Skull Tower generates wealth via Planar Tariffs:
[Planar Merchants / Explorers] ---> [The Skull Gates] ---> [10% Flat Transit Tax]
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Yields: 5,000 - 30,000 gp/month
The ruler can levy a flat 10% transit tax on all planar merchants, mercenaries, and adventuring parties passing through the tower's gates.
The Garrison Upkeep Check: Because Skull Tower is a focal point for cross-dimensional factions, the domain requires a massive garrison. The monthly upkeep for defenders—including specialized anti-magic units, golems, and heavy-weapons cohorts—must equal at least 50% of the gross gate tariff revenue to prevent an immediate coup or planar invasion.
Garrisoning with Exotic Units
Skull Tower allows you to recruit forces completely unavailable in standard fantasy realms. When assembling an army using the Domains at War framework, the ruler can hire:
Phraint Phalanxes: Treated as heavy infantry with elite morale (+2) and natural armor piercing traits.
Techno Sapper Squads: Disarm castle fortifications and traps at triple the speed of traditional engineers using high-frequency plasma torches.
To run the World Gates of Skull Tower as a dynamic economic driver using the ACKS II domain and market mechanics, the gate is treated as a Class I Planar Market Venture. Instead of tracking individual merchant wagons, a ruler or Judge tracks the Monthly Shipping Manifests.
This system uses the ACKS II trade engine but introduces Planar Flux, allowing domain rulers to tax exotic imports or export terrestrial goods to alien dimensions.
1. The Gate Economy Framework
Every month during the Domain Turn, the ruler calculates the Gate Trade Value (GTV). The baseline GTV is determined by the size and stability of the market surrounding the tower:
Skull Tower Ruins (Unsecured / Wild): Base GTV = 2,500 gp
Fortified Borderland Outpost: Base GTV = 10,000 gp
Secured Planar Free-Port (Class II Market Equivalent): Base GTV = 40,000 gp
The Tariff and Unrest Mechanics
The ruler can levy a Planar Tariff on imports and exports moving through the gates:
Standard Tariff (5%): Normal operations. Generates standard revenue.
Aggressive Tariff (15%): Double revenue, but increases local Domain Unrest by +1 due to black-market smuggling rings springing up in the catacombs.
Prohibitive Tariff (30%): Triple revenue, but increases Domain Unrest by +3 and triggers a roll on the Planar Smuggler Strike event table.
2. Monthly Planar Flux Table (d100)
At the start of each month, roll 1d100 to determine which dimensional faction or empire currently holds the dominant trade manifest through the Skull Tower World Gates. This modifies the base GTV and dictates available goods.
| d100 | Planar Trade Manifest | GTV Modifier | Primary Import (Available to Buy) | Primary Export (Demanded by Gate) |
| 01–15 | The Techno-Foundries of Omega-Prime | +50% | Power Cells, Cyber-Parts, Lasers | Raw Iron Ore, Unrefined Mithril |
| 16–30 | The Obsidian Slavelords of the Red Sun | +20% | Exotic Beasts, Gladiators, Narcotics | Terrestrial Grain, Fresh Water |
| 31–45 | The Phraint Chitin-Hive Conglomerate | +0% | Hyper-Dense Alloys, Composite Bows | Alchemical Acid, Honey / Sugar |
| 46–60 | The Astral Merchant Cartel of the Void | +100% | Ancient Relics, Rare Spells, Gems | Finished Luxury Goods, Artwork |
| 61–75 | The Chrono-Dilation Free-Traders | -25% | Liquid Time, Preserved Artifacts | Historical Texts, Living Livestock |
| 76–90 | The Abyssal Flesh-Weavers | +10% | Bio-Constructs, Mutagenic Chem-Stims | Humanoid Corpses, Souls / Essence |
| 91–00 | The Cosmic Storm (Gate Malfunction) | -100% | None (Gate is physically unstable) | None (Trade route collapsed) |
3. Exotic Import/Export Goods Table
When a player characters or independent merchants want to actively buy or sell bulk merchandise through the gate, roll 1d20 on this table to see what specialized cargo containers have arrived on this month's manifests.
| d20 | Cargo Manifest Item | Lot Size | Base Purchase Cost | Terrestrial Market Value | Risk / Legality Factor |
| 1 | Omega-Prime Power Cells | 1 Crate (50 cells) | 10,000 gp | 15,000 gp | Highly volatile; explodes if exposed to magical fire. |
| 2 | Refined Plasteel Sheeting | 10 Tons | 5,000 gp | 7,500 gp | Can be used to reduce Stronghold building costs by 20%. |
| 3 | Deodand Hunting Hounds | Pack of 1d6 | 3,000 gp | 4,500 gp | Require raw meat daily; 5% chance per month to turn on handlers. |
| 4 | Phraint Chitin Armor Lots | 10 Suits | 4,000 gp | 6,000 gp | Extremely light plate-equivalent armor; highly sought by mercenaries. |
| 5 | Hyper-Space Narcotics (Lotus-Dust) | 1 Small Case | 2,000 gp | 8,000 gp | Illegal. Triggers a city-wide guard inspection if moved out of hex. |
| 6 | Stasis-Preserved Alien Seeds | 1 Vault Box | 6,000 gp | 9,000 gp | Can be planted to permanently increase a domain's land yield by 5%. |
| 7 | Cybernetic Limb Replacements | 1d4 Units | 8,000 gp | 12,000 gp | Requires a Techno or Master Cyberneticist to safely implant. |
| 8 | Liquid Promethium Jet-Fuel | 50 Barrels | 5,000 gp | 7,000 gp | Highly explosive; counts as heavy ammunition for siege engines. |
| 9 | Crashed Probe Salvage Scrap | 1 Bulk Lot | 3,000 gp | Varies | Yields 1d4+1 rolls on the Techno Workshop Crafting Table. |
| 10 | Mutagenic Growth Serums | 10 Vials | 4,000 gp | 6,000 gp | Used to speed up monster cross-breeding projects by 50% in ACKS II. |
| 11 | Astral Silk Textiles | 20 Bolts | 3,500 gp | 5,500 gp | High-end luxury trade good; doubles standard merchant caravan profit. |
| 12 | Vibro-Blade Weapon Shipments | 20 Swords | 6,000 gp | 9,000 gp | Weapons ignore leather/padded armor entirely; elite troop gear. |
| 13 | Unstable Fusion Reactor Cores | 1 Core | 15,000 gp | 25,000 gp | Required to power Arduinian Heavy Power Armor or Foundry bases. |
| 14 | Alien Slave Cohorts | 50 Laborers | 2,500 gp | 4,000 gp | Reduces domain garrison or construction labor costs by 10%. |
| 15 | Holographic Grid Projectors | 2 Units | 7,000 gp | 10,000 gp | Can be installed in strongholds to grant defense against sieges. |
| 16 | Interstellar Spice Cargo | 5 Crates | 4,000 gp | 8,000 gp | Highly sought after by terrestrial emperors and high nobility. |
| 17 | Malfunctioning Labor Droids | 1d4 Droids | 5,000 gp | 7,500 gp | Can replace 20 human laborers each if repaired by a Techno. |
| 18 | Void-Hardened Steel Ingots | 5 Tons | 8,000 gp | 12,000 gp | Used to forge weapons with a permanent +1 non-magical hit bonus. |
| 19 | Memory Disks (Ancient Data) | 1 Cache | 10,000 gp | Varies | Grants an automatic success on one future technological blueprint roll. |
| 20 | Bio-Luminescent Light Spores | 100 Jars | 1,000 gp | 2,000 gp | Permanent cold-light source; heavily demanded by subterranean miners. |
4. Resolving a Trade Turn
To run a transaction through the Skull Tower World Gates during the monthly phase:
Check Planar Flux: Roll 1d100 to find out who is trading through the gate this month and apply the GTV modifier.
Calculate Tariff Income: The domain ruler automatically collects Tariff % × Modified GTV in gold pieces as pure tax revenue into the kingdom's treasury.
Roll Available Cargo Lots: Roll 1d20 three times on the Exotic Import/Export table to see which specific bulk items are available for players or local merchant syndicates to purchase, speculate on, or ship to standard terrestrial markets downriver.
This d20 table is designed for Levels 4–6 of Skull Tower, targeting mid-level parties (Levels 4–7). In accordance with the ACKS II dungeon ecology framework, this table combines both concrete monster encounters (with quantities scaled to tactical threat parameters) and systemic environmental events that shift the dungeon's logistical state.
Skull Tower: Levels 4–6 Wandering Monster & Event Table
| d20 | Encounter / Event Type | Details & ACKS II Mechanical Scaling | | :---: | :| :| | 1 | Phraint Vanguard | 1d4 Phraints. AC 5, HD 3+3, Att 1 × weapon (greatsword or composite bow), Move 120ft, SV F4, ML +1, AL Neutral. Highly coordinated insectoid warriors. They leap up to 30ft into combat, gaining a +2 to hit on charge attacks. They are hostile only if the party interferes with their current hunting mission. | | 2 | Deodand Pack | 1d6 Deodands. AC 4, HD 4+2, Att 2 × claws (1d4), 1 × bite (1d6), Move 120ft, SV F4, ML +2, AL Chaos. Carnivorous, pitch-black humanoids that radiate unnatural malice. They surprise on a 1–4 on 1d6. If they hit with both claws, their bite attack deals double damage. | | 3 | Techno-Scavenger Squad | 1d4+1 Rival Human Technos (Level 3). AC 6 (Mesh Vest), HD 3, Att 1 × Laser Pistol (1d6+1) or vibro-blade (1d6), Move 120ft, SV T3, ML 0, AL Neutral. Armed with 1st-level Schematics. They are actively hunting for Technic Salvage and will try to extort, rob, or ambush the party if they think they have the upper hand. | | 4 | Thrak Marauders | 1d3 Thraks. AC 7 (Chitin), HD 6, Att 1 × massive pincer (2d6) or weapon, Move 90ft, SV F6, ML +1, AL Chaos. Brutal, reptilian-insectoid hybrids. They possess a high strength threshold; any target hit by a pincer must make a Save vs. Paralysis or be pinned (unable to move, taking automatic pincer damage each round until they break free). | | 5 | Dimensional Shambler | 1 Shambler. AC 5, HD 5, Att 2 × claws (1d8), Move 60ft, SV F5, ML +3, AL Chaos. A cosmic horror that steps through solid walls via phasing rifts. It is immune to non-magical or non-technic weapons. If it hits a target with both claws, it attempts to grapple and phase them into a hostile pocket dimension on the following round (Save vs. Spells to resist). | | 6 | Cybernetic Zombie Pack | 2d4 Cyber-Zombies. AC 3 (Steel Plating), HD 2, Att 1 × slam (1d6) or rusted bayonet (1d6), Move 60ft, SV F1, ML N/A (Fearless), AL Chaos. Reanimated corpses augmented with crude cybernetics. They do not check morale. They take half damage from piercing weapons but are highly vulnerable to electrical or EMP attacks, which instantly short-circuit them. | | 7 | Lathi Stalker | 1 Lathi. AC 6, HD 7, Att 2 × claws (1d6), 1 × energy lash (1d10), Move 150ft, SV F7, ML +2, AL Chaos. A shifting, predatory entity from the deep outer voids. It can turn completely invisible at will (Hide in Shadows 85%). Attacks out of invisibility grant it a +4 to hit. | | 8 | Kobbit Tunneling Party | 2d6 Kobbits. AC 2, HD 1-1, Att 1 × shortsword (1d6) or sling (1d4), Move 90ft, SV T1, ML -1, AL Neutral. Distant, hyper-cautious sub-terran relatives of halflings. They are mapping the level. They are entirely non-hostile unless cornered and will gladly trade accurate mapping data regarding nearby traps for standard rations or shiny junk. | | 9 | Malfunctioning Defense Drone | 1 Hover-Drone. AC 8 (Skittering Skiff), HD 4, Att 1 × Pulse Laser (1d8), Move 150ft (Fly), SV F4, ML N/A, AL Neutral. A floating security automated unit with a fried targeting matrix. It fires indiscriminately at any moving organic creature within 90ft. It can be looted for 1d3 intact Power Cells if disabled without being blown up. | | 10 | Star-Refugee Mercenaries | 1d3 Alien Humanoids. AC 4 (Deflector Fields), HD 5, Att 1 × Plasma Rifle (2d6), Move 120ft, SV F5, ML +1, AL Neutral. Out-of-work dimension travelers looking for a way home. They can be hired as elite retainers for the duration of the dungeon delve if the party pays them a premium upfront fee of 500gp per level in pure silver, gold, or functional tech components. | | 11 | Event: World Gate Backwash | The floor trembles as a distant nexus gate cycles open on an adjacent level. A wave of chronal distortion washes through the corridor. All active spell durations, light sources, and active Techno Schematics are instantly reduced by 1d4 turns as time briefly dilates. | | 12 | Event: Radiation Leak | The party steps into a zone contaminated by a ruptured power conduit from an ancient machine room. All characters must immediately make a Save vs. Poison/Radiation. Failure results in the immediate loss of 1d4 Constitution points due to cellular sickness (restorable only via high-level Cleanse magic or advanced medical stims). | | 13 | Event: Faction Skirmish | The party encounters a chaotic battlefield mid-corridor: 1d4+1 Phraints are actively locked in a lethal melee combat against 1d6 Deodands. The party can choose to intervene to gain favor with a faction, sneak past during the chaos, or ambush the survivors. | | 14 | Event: Gravity Inversion Zone | The artificial gravity grid in this 60-foot stretch of hallway fails completely. Gravity shifts upside down for 2d6 rounds. Anyone in the area takes 1d6 falling damage as they plummet to the ceiling. Movement is reduced to a crawl (one-fourth speed) unless characters have magnetic footwear or levitation. | | 15 | Event: Technic Scavenge Node | The party stumbles onto the structural wreckage of a destroyed extra-dimensional pod or machine interface. A Techno or character with Ancient Lore (Technology) can spend 1 turn to roll a scavenging check, yielding 2d6 × 100gp worth of Technic Salvage Value (SV). | | 16 | Event: Temporal Echo | The ghostly, translucent apparitions of a high-level adventuring party from 100 years in the future (or past) walk straight through the corridor, speaking in an unknown language. They ignore the PCs completely, but watching their path reveals the exact location of a hidden pit trap further down the hallway. | | 17 | Event: Power Grid Overload | Wall panels crackle with blue static electricity. All electronic gear, blasters, and active power suits spark violently. Every power cell currently carried by the party loses 1d3 active charges due to sudden magnetic drainage unless stored in lead-lined shielding bags. | | 18 | Event: Toxic Slime Inundation | A rusted overhead conduit bursts open, flooding the path ahead with a slow-moving wave of neon-green acidic slime. The corridor is impassable for the next 2d4 hours unless the party uses plasma torches or magical fire to scorch a path through the caustic sludge. | | 19 | Event: Market Scout Caravan | A strange merchant entourage from the Skull Tower Surface Citadel approaches. Led by a cloaked High-Elf trader and escorted by robotic guards, they are willing to buy dungeon treasures or sell basic adventuring gear and standard ammunition at a 50% markup. | | 20 | Event: Spatial Fold | The layout of the dungeon twists dynamically. The door or corridor the party just passed through now connects to a completely different room on the opposite side of the map level. Returning to safety requires navigating an entirely new path forward. |
Implementation Guidelines for the Judge
Encounter Frequency: Roll a d20 once every 2 turns (20 minutes) of exploration time while the party is navigating the mid-levels of the tower. An encounter or event occurs on a roll of 1–3.
Morale Modifications: Arduinian creatures are notoriously stubborn or unpredictable. If a monster roll indicates a Chaos alignment, they will rarely check morale until their group has been reduced to one-third of its original starting numbers.
Tracking Salvage Value: Any defeated mechanical entity (such as the Hover-Drone or Cyber-Zombies) can be harvested for raw parts using the ACKS II component rules, providing structural wealth to fuel a Techno's workshop fabrication projects.
