A d100 Encounter Table Tailored For classic B/X Dungeons & Dragons (and compatible Old School Renaissance systems).

 Here is a d100 encounter table tailored for classic B/X Dungeons & Dragons (and compatible Old School Renaissance systems).

Yes I totally stole this photo from Wayne's Books from here. 

To keep this highly functional for a standard B/X campaign, the table is structured around the classic dungeon tier logic: Levels 1 to 3. It balances standard low-level fantasy staples with faction dynamics, environmental hazards, and weird "OSR-style" situations that force players to interact with the environment rather than just rolling for initiative.

d100 Low-Level (Dungeon Levels 1–3) Encounter Table

d100	Encounter	No. Appearing	Activity / Current State
01-03	Acolytes (Evil)	1d8	Chanting in a low drone, carrying a sacrificial profane idol.
04-06	Amphiunder / Frogfolk	2d4	Smearing paralyzing slime onto stone tipped javelins.
07-09	Bandits	1d6+2	Setting a tripwire trap to ambush a rival dungeon faction.
10-12	Beetle, Fire	1d8	Gnawing on old torches; their glands glow with ambient light.
13-15	Beetle, Oil	1d4	Squirting blistering oil at a swarm of harmless centipedes.
16-18	Berserkers	1d4+1	Frothing at the mouth, desperately trying to break down a stuck door.
19-21	Carcass Crawler	1	Feasting on a fresh ghoul carcass; completely distracted unless approached.
22-24	Centipede, Giant	2d4	Dropping silently from the ceiling cracks onto the rearmost party member.
25-27	Crab, Giant River	1d2	Wandering up from a flooded basement level, smelling of sulfur.
28-30	Gargoyle	1	Perched perfectly still above an archway, waiting for a lone target.
31-33	Gelatinous Cube	1	Sweeping the hallway. Trapped inside it is a glowing, un-melted iron key.
34-36	Ghouls	1d4	Whispering to each other in a dead language, burying a stolen chest.
37-39	Gnolls	1d6	Argue loudly over how to split up a dead mule's hindquarters.
40-42	Goblins	2d6	Driving a small flock of blind subterranean goats toward a pen.
43-45	Gray Ooze	1	Mimicking a harmless wet puddle right in front of a treasure chest.
46-48	Hobgoblins	1d6	Marching in strict military lockstep, scouting for an invading Orc warband.
49-51	Kobolds	3d6	Retreating in absolute panic from something deeper in the dungeon.
52-54	Lizard Men	1d6	Carrying a heavy clay jar full of swamp-water and strange, squirming eels.
55-57	Lizard, Tuatara	1	Dozing near a hot steam vent; its pebble-like skin looks like a wall section.
58-60	Morlocks	1d8	Tracking the party by scent from the shadows just outside torch radius.
61-63	Orcs	2d4	Whipping a captured goblin who is forced to test a suspect floor lever.
64-66	Rat, Giant	3d6	Scurrying in a massive wave away from a sudden, localized gas leak.
67-69	Rock Baboons	1d6	Sarcastic and loud; pelting passersby with ancient, petrified dung.
70-72	Shadow	1	Following the PC's actual shadows, slowly draining the room's temperature.
73-75	Skeleton	2d4	Mechanically sweeping dust back and forth across a shattered mosaic floor.
76-78	Snake, Pit Viper	1d3	Coiled inside an empty wall alcove, agitated by the party's light source.
79-81	Spider, Crab	1d4	Camouflaged on a tapestry, waiting to drop down with a +2 bonus to surprise.
82-84	Spider, Black Widow	1	Guarding an enormous egg sac woven into a rotting wooden portcullis.
85-87	Stirges	1d10	Hanging like leathery fruit from old iron pipes, waking up as torches pass.
88-90	Thoul	1d2	Posing as a wounded, weeping human prisoner to lure someone close.
91-93	Troglodytes	1d4	Squatting in a circle, oiling their scales. The stench is noticeable 60' away.
94-96	Zombies	1d6	Shuffling aimlessly, wearing the tattered silk tunics of a long-dead cult.
97-98	Wandering Merchant	1d3	A heavily armed subterranean trader with two mutant retainers. Neutral.
99	Rival Adventurers	1d4+2	A low-level party (Fighter, Cleric, Magic-User, Thief) looking to rob the PCs.
100	The "Boss" Roll	1	Roll on the Level 4-5 table, or introduce a major local faction leader.

3 Pillars of B/X Encounter Procedures

When rolling an encounter from this table, remember to apply the classic B/X procedural checks to see how the situation actually plays out. It's rarely a straight-up fight to the death.

1. Distance & Surprise

Roll 1d6 for surprise for both the party and the encounter.

• Both surprised / Neither surprised: Encounter begins at 2d6 x 10 feet away.

• One party surprised: The unsurprised group can choose to flee, hide, or attack with a free round. The encounter begins at 1d4 x 10 feet away.

2. The Reaction Roll (2d6)

Unless the monsters are mindless undead or completely driven by hunger, roll 2d6 modified by the active PC’s Charisma to determine their initial disposition:

• 2: Immediate Attack

• 3–5: Hostile / Unfriendly (May attack, demand tribute, or mock)

• 6–8: Uncertain / Wary (Waiting to see what the PCs do; open to parley)

• 9–11: Indifferent / Friendly (Will talk, trade information, or let the party pass)

• 12: Enthusiastic / Helpful (Offers an alliance or valuable dungeon intel)

3. Morale Checks (2d6)

Monsters don't want to die. Roll 2d6 against the monster's Morale rating under two specific triggers:

1. When the first monster in their group is killed or incapacitated.

2. When the monster group is reduced to half its original numbers.

• If the roll is greater than the monster's morale score, they break and run, surrender, or beg for mercy.

Meditations on the classic In Search of the Unknown (Module B1, written by Mike Carr in 1978) module Adapted To OSR Rpg systems especially The Adventurer, Conqueror, King Second Edition - Part Four

 In ACKS II, Level 2 of Quasqueton transitions from a military fortification to a hostile subterranean wilderness. Wandering encounters here are not just combatants—they are environmental pressures that test the party’s resource management (light, rations, sanity) in a damp, enclosed ecosystem. This post  picks right up from Meditations on the classic In Search of the Unknown (Module B1, written by Mike Carr in 1978) module Adapted To OSR Rpg systems especially The Adventurer, Conqueror, King Second Edition - Part III

Check for a wandering encounter every 2 turns of exploration. An encounter occurs on a roll of 1 or 2 on a $1d6$ (increased danger due to the wild nature of the caverns).

Quasqueton Level 2: Subterranean Hazard Table ($1d10$)

Roll	Encounter / Hazard	ACKS II Statistics & Mechanical Behavior
1	The Stench (Environmental)	A massive plume of rot-gas vents from a floor fissure. Save vs. Poison or suffer -2 to all attack throws and proficiency checks for $1d6$ turns due to vomiting/nausea. Characters failing by 5+ are incapacitated for 1 turn.
2	Troglodyte Hunting Party	4x Troglodytes (AC 4, HD 2, hp 10 each, Morale +1). Ambush: They use Chameleon Skin to hide in the damp rock walls; they receive a +2 bonus to surprise. They target the character carrying the light source first.
3	Unstable Scree (Hazard)	A floor section is a disguised slope of loose rock over a 20ft drop. Saving Throw: Each character must make a Dexterity/Save vs. Paralysis throw. Failure means sliding into the pit for $2d6$ falling damage and becoming trapped until rescued.
4	Giant Centipedes	1d6 Giant Centipedes (AC 0, HD 1/2, hp 3 each, Atk: Bite +0, Damage 0 + Save vs. Poison). Effect: If the save fails, the victim is paralyzed for $2d6$ turns. The centipedes prioritize paralyzed prey, dragging them into ceiling cracks.
5	Subterranean River (Obstacle)	The tunnel gives way to a fast-moving, 15ft wide underground river. Crossing: Requires a rope and a Strength/Athletics check to secure an anchor. If the check fails, the character is swept downstream for $1d6$ bludgeoning damage and separated from the party.
6	Carrion Crawler	1x Carrion Crawler (AC 2, HD 3+1*, hp 18, Atk: 8x Tentacles +0, Damage: Paralysis). Tactics: It drops from the ceiling above the party. Any hit by a tentacle forces a Save vs. Paralysis. It attempts to paralyze the strongest-looking PC and retreat.
7	Luminous Fungi (Hazard/Resource)	The walls are coated in glowing spores. Effect: Anyone within 10 feet must Save vs. Poison or start hallucinating for $1d4$ hours (-4 penalty to Wisdom/Int checks). Harvest: A Mage/Alchemist can spend 1 turn to scrape 2 doses of "Glowing Paste" (acts as a 1-hour light source if smeared on a staff).
8	Lost Explorer (NPC)	A survivor from a previous expedition (or a wounded Orc/Beastman from L1). They are starving and delirious. Interaction: If healed or fed, they provide a 1-in-6 hint about the location of the Lower Vault (see below) but will panic if forced into combat.
9	Rust Monster	1x Rust Monster (AC 2, HD 5*, hp 22, Atk: Antennae +0, Effect: RUST). Tactics: It ignores flesh, relentlessly charging the party member with the most metal armor/weapons. ACKS II Note: Plate armor/Shields are destroyed on a failed save; weapons take -1 penalty until repaired.
10	The Quake (Event)	A localized tremor shakes the ceiling. Effect: Stalactites fall in a 30ft radius. Everyone in range must make a Save vs. Blast or take $2d6$ piercing damage. The path behind the party is permanently sealed by falling rock, forcing a new route.

Referee Mechanics: The "Deep Dark" Environment

When running encounters in Level 2, apply these ACKS II environment modifiers to maintain the tension of the lower caverns:

• Light Suppression: Due to the perpetual humidity and cave mist, all non-magical light sources (torches, lanterns) have their radius halved. A torch illuminates only 15 feet; objects beyond 30 feet are in total darkness.

• Acoustic Distortion: The constant dripping of water and echoing tunnels impose a -2 penalty to all Listen at Doors checks. Conversely, the party’s own noise (clanking armor, shouting) travels 2x further, increasing the frequency of wandering monster checks.

• The "Lost" Mechanic: If the party rolls a 1 on a $1d6$ while wandering, they have lost their way in the winding limestone fissures. They must spend 1 full turn backtracking to regain their bearings, consuming rations/light and triggering an automatic check for a wandering monster.

To anchor the deep end of the Caverns of Quasqueton under ACKS II metrics, the treasures hidden within Zelligar’s personal, untouched subterranean vault must reflect his status as an eccentric, high-level arcanist.

In ACKS II, permanent magic items are incredibly rare and highly regulated by campaign economics. A single true magic item can fund an entire domain or represent months of magical research. Below is the manifest of the inner vault, hidden behind a stone-sleeved puzzle door in the deepest limestone recess of Level 2.

1. The Gold Cache (The Foundation Wealth)

Zelligar kept his emergency reserves in minted bullion rather than loose, bulky coinage. This wealth is stored inside a reinforced, lead-lined iron chest bolted directly into the bedrock.

• Imperial Trade Ingots: 12x Stamped Electrum Bars.

  • Value & Weight: Each bar is worth exactly 100 gp and weighs 1 Stone (1.0 St each).

  • Total: 1,200 gp value / 12 Stone weight.

• The Minted Reserves: A heavy canvas sack containing 800 ancient, heavy platinum pieces (pp) from a fallen empire.

  • Value & Weight: In ACKS II, platinum trades at a 5:1 ratio to gold. This sack is worth 4,000 gp and weighs 8 Stone (800 coins = 8 Stone).

• Logistical Reality: Total coin/bullion value is 5,200 gp (granting 5,200 XP upon successful extraction to a civilized market), but it carries a staggering combined weight of 20 Stone. A low-level party will need hirelings, pack mules at the surface, or multiple highly dangerous trips to extract this wealth.

2. The Alchemical Dispensary (Liquid Capital)

Stored inside a dust-covered cedar rack are Zelligar’s preserved experimental fluids. These count as precious Trade Goods or usable tactical assets.

• 3x Flasks of "Dragon’s Breath" (Alchemist's Fire): Thick, volatile red oil.

  • Weight: 0.1 Stone each (1 item slot).

  • ACKS II Mechanics: Can be thrown as a missile weapon (range 10/30/50). On a hit, it bursts, inflicting $1d8$ fire damage on impact and an additional $1d4$ damage on the following round. Ignites wooden structures or doors instantly.

• 2x Vials of Vitriol (Concentrated Acid): Kept in reinforced dark-glass vials.

  • Weight: 0.1 Stone each (1 item slot).

  • ACKS II Mechanics: Deals $2d4$ acid damage if thrown at an opponent. More importantly, it can be poured onto iron locks or door hinges, dissolving them silently over 3 turns and bypassing the need for a Thief's Open Locks roll.

• 1x Jar of Universal Solvent: A clear, odorless gel.

  • Weight: 0.2 Stone.

  • Value: Worth 300 gp to an Apothecary or Wizard's guild for magical research. It instantly dissolves any non-magical adhesive, tar, or web spell.

3. The Permanent Magic Items (The True Prizes)

These items are hidden inside a stone sarcophagus protected by a dormant, minor magical ward that causes a character's hair to stand on end when approached.

The Cinnabar Band (Ring of Fire Resistance)

A heavy copper ring set with a raw, uncut carnelian stone. It bears Zelligar’s personal sigil etched on the inner band.

• Weight: 0.0 Stone (Negligible).

• ACKS II Mechanics: The wearer is completely immune to normal fire (torches, boiling water, burning oil). Against magical fire or dragon breath, the wearer receives a +2 bonus to all Saving Throws and all damage suffered is automatically halved.

• Campaign Value: If sold to a Wizard's Guild in a Market Class II city, it commands a price of 2,000 gp (but yields no XP if sold; XP is only gained if kept or donated to a temple/lord for political favor).

The Arcanist’s Lexicon (Enchanted Spellbook)

A massive, iron-bound tome wrapped in shimmering basilisk hide. The pages are made of fine vellum that does not decay or burn.

• Weight: 1.5 Stone (Bulky; requires dedicated space in a backpack).

• The Contents: This is Zelligar’s working notebook. It contains the complete, transcribed casting formulas for the following spells:

  • 1st Level: Hold Portal, Light, Shield

  • 2nd Level: Continual Light, Invisibility

  • 3rd Level: Fireball (Requires a 5th-level Mage to cast, but a 1st-level Mage can scribe it or use it for study).

• ACKS II Arcane Utility: A Mage character can spend 1 week of downtime per spell level to copy these formulas into their personal spellbook. Alternatively, the book contains enough raw magical theory notes to count as 1,500 gp worth of Magic Research Materials, directly offsetting the gold cost required for a Mage to research new custom spells or brew potions.

Referee Guidance: The Vault's Final Defense

Zelligar didn't leave this vault entirely unguarded. The iron chest containing the platinum coins is rigged with a Needle Trap coated in a long-lasting paralytic toxin (Thief Find Traps 15+ to locate).

Triggering the trap forces an immediate Save vs. Poison. A failure doesn't cause death, but it inflicts Total Paralysis for $2d6$ hours. If the party triggers this while deep in Level 2, they must carry their paralyzed ally out through the Cavern Encounter Table, making them prime targets for the hunting Carrion Crawler or Troglodyte Stalkers roaming the outer fissures.