15 Biome Encounter Tables

 I enjoy ecosystem-based encounter tables, but the very best are hard to find. They can be so broad as to lack any evocation of place, as with endless "forest" tables that list all the mainstay monsters, plus or minus a treant. I like to have many small regions of only a handful of hexes, which might put one plains next to another plains with an identical encounter table. What's more, it's hard to find meaningfully different biome-based encounter tables, since the most obvious choices are always included. If you're not including dire camels on your desert encounter table, where are you going to put it?

Here it pays to be more specific. Rather than a "forest" table, you can roll on an "elfy coniferous forest" table and get specific encounters with a better sense of their intentions, appearance, and accouterments. I beg the world to generate many small, specific encounter tables that can nevertheless be pressed into service for piecemeal hexmaps, hastily assembled two-shots, or inspiration for full adventures.

To that end, I've made fifteen d6 encounter tables for more specific biomes. I did this by randomly generating lots of 6 monsters from Old School Essentials without any attention paid to hit dice or typical environment, then designating the biome after the fact. This forced me to make creative decisions about why two unlike creatures would be found in the same place. Once I had the biomes named, I noted the number appearing according to OSE and invented example behavior for negative, neutral, and positive reaction rolls according to this format:

(negative/neutral/positive)

This step was important to me because I'm often stumped by uncharacteristic reaction rolls at the table and I though the work of brainstorming ahead of time was worthy, and also to further characterize the region.

Induction by Josh Pierce

As I worked on this project I noticed how useful some parts of the classic D&D monster write-ups were for this project. Number Appearing was constantly helpful (except when they were churlishly listed as "0",) as were any notes about a monster's affinities and hatreds. Behavior of any kind was often folded into one of the example reactions, and characteristic attacks let me vary even the negative reactions. Fighting to the death can be easily overdone in D&D, and I tried to give even chaotic or animal enemies some specific goal where appropriate.

If you want to extend the d6 tables, I recommend adding low-level creatures, since total randomness in monster selection makes the areas quite dangerous. (Remember, encountering dozens of humanoids likely means most are not patrolling with bardiches in hand.) A good template for extending into a d10 table might be:

7. 1-HD humanoids or wildlife
8. familiar faces (someone the party fled, helped, etc.)
9. rival adventuring party
10. Roll 1d6 twice and combine

Here are the 15 encounter tables, and a link to the OSE monster SRD to inspire your own:

Haunted War-torn Jungle
1. Bats! 75% 1d00 normal, 25% 1 giant bat. (attack and combust/size up/aid in hunting)
2. Squad of 2d6 Veterans (opposed alignment/deserters/ideologically aligned)
3. Elemental, lesser. 50% water, 50% fire. (punish/ignore/heal the land)
4. Haunting of 1d8 Spectres (attack armed humanoids/warn of war’s folly/lead to bodies and loot)
5. Dragon, green (flyby breath attack/accept tribute/offer task)
6. Crocodile. 75% normal, 20% large, 5% giant. (drag off weak victim/ignore/offer advice or a ride)

Degraded Pool-ridden Shore
1. Cloud of 3d12 Stirges emerge from a pool (dive attack/hover over pool/depart from corpses with loot)
2. Platoon of 4d6 Hobgoblins (capture for ransom/conscript/exchange information)
3. Pod of 1d3 Whales, sperm. May beach themselves. (emerge to swallow whole/swim by/disgorge cargo) 4. Herd of 1d10*10 Horses. (stampede/grazing on goosefoot/friendly tamers scoping out the best)
5. Jaunt of 2d6 Nobles, each with a squire and 1d10 fighter retainers. (covering up association with hobgoblins/enjoying a terrible beach day/hiring champions)
6. Pride of 1d4 Manticores (track and ambush those who stop to rest/defend nest/trade area knowledge for meat)

Corrupt Trading Coast
1. 1d2 Octopodes, Giant (grab d8 people and objects/observe from camouflage/offer watery trinket)
2. Platoon of 1d6+1*10 Dervishes. Mounted. Half are light lancers, a quarter are cataphracts, a quarter are archers. Dislike orcs. (capture as spoils/lecture and ask directions/engage in charity and personal improvement)
3. Invisible Stalker (ransack for clues about target/wildlife give away presence/make a kind connection)
4. Clump of 1d3 Caeciliae (swallow whole/guard hoard/acts like a friendly dog that doesn’t know its size)
5. Band of 1d6*10 Orcs. For every 20, there is a 1-in-6 chance of an ogre. Dislike dervishes (send night squad to rob/send junior members to challenge/trade rare goods)
6. Family of 1d4 Triceratopses (charge/skittish/curious)

Ancient Cave-ridden Plains
1. Hydra (stalk/seek out water/cuddle)
2. Hawks. 75% 1d6 normal, 25% 1d3 giant hawks.(swoop or abduct/inspect from afar/warns of a nearby cave)
3. Hunting Party of 1d6+1*10 Dervishes. Mounted. Half are light lancers, a quarter are cataphracts, a quarter are archers. (capture and escort out of the area/trade advice/ask for help hunting servants)
4. Pit of 1d6 Wyverns (ambush/lead to rival wyverns/throw gold at party to cover a getaway)
5. Pit of 1d6 Wyverns.(aggressive display/guard cave/offer shelter)
6. Crash of 1d6 Titanotheres (stampede/circle together/escort)

Alpine Pool Mountain
1. Expedition of 3d6 Traders with 1d6 mules. (pawn off boondoggles/sell furs and clothes/share brandy)
2. Party of 1d10 Thouls (Drive off/confiscate elves and fire supplies/trade for meat)
3. Clutter of 1d3 Spiders, Giant. Tarantellas. (ambush/block trail back with webs/inadvertently show treasures)
4. Grove of 1d6 Treants. Conifers. (drive off/chat/share magic sap)
5. Lounge of 1d6 Basilisks (attack in ostentatious display/watch from the shadows/give magical scales)
6. Community of 1d4*10 Neanderthals (throw rocks and shout/trade through gesture/offer hospitality)

Intertidal River Canyon
1. Wing of 2d8 Hippogriffs (prey upon/survey/befriend)
2. Herd of 1d10*10 Horses (stampede/migrating quickly past/paying homage to party and hippogriffs)
3. Coincidence of 1d10 Lizards, Giant. Stats as gecko. (bowl over/beg for food/lead to hiding place)
4. 1d2 Fish, Giant. Mudskipper, as catfish. (ambush from bank/guard shiny in the shallows/offer ride)
5. Cast of 1d6 Crabs, Giant (pinch apart/bar way/invite to rave)
6. Ambuscade of 5d8 Troglodytes (eat/bully into trades/offer roll in hippogriff hunt pageant)

Chimney Hill Caves
1. Hydra (oh shit this one breaths fire/reveal hidden cavern/mutely conscript in hobwar)
2. Convention of 4d6 Hobgoblins (arrest and interrogate/give directions to anywhere not nearby/demand fiery oration)
3. Clump of 1d3 Purple Worms (swallow whole/cut off backtracking/lead to underground destination)
4. Party of 1d10 Thouls (hunt/ask party to join in their hunt/join party for a time)
5. Pack of 2d10 Rats (engulf/flee/ask for help in tinny voice)
6. Scandal of 2d4 Harpies (charm and harm/insult/follow for scraps while gossiping)

Abandoned Forest Route
1. Noise of 1d6*10 Orcs. For every 20, there is a 1-in-6 chance of an ogre. (scare off/trade woodwork/send a trio to accompany party)
2. Wing of 2d8 Hippogriffs (carry off/shadow from overhead/beg meat of party)
3. Ambuscade of 5d8 Troglodytes (erupt from hollow to take captives/argue for a toll/conspire with party against orcs or lycanthropes)
4. Gelatinous Cube (pursue/run into/guard faithfully)
5. Pack of 1d6 Blink Dogs (drive off for unknown purpose/accept pets/lead to interesting site)
6. Misery of 2d6 Lycanthropes. Werewolves. (heavy silver toll by day, indoctrinate by night/brusquely trade/beg for compassion)

Occupied Ranging Plains
1. Mastication of 2d8 Ghouls (order party to secluded eating spot/bully/sell shoes, jewelry, and household supplies)
2. Platoon of 6d10 Goblins. 1-in-5 chance they ride wolves. (disappear someone/interrogate/allow you to offer them drinks)
3. Invisible Stalker (seeks party leader/eavesdrops and reports to master/insurgent sabotage)
4. Cavalcade of 2d10 Centaurs (sell out to the regime/beg for supplies/aid in daring missions)
5. Pit of 1d4 Snakes. Giant rattlers. (attack without warning/give warning/foreshadow secret resistance door knock)
6. Herd of 1d6 Titanotheres (stampede/graze wearily/conceal refugees tied underneath them)

Open Water Archipelago
1. Pod of 1d3 Whales, Sperm.(ram or swallow whole/wave as they pass/lead to another ship)
2. Swarm of 2d6 Robber Flies (ambush from shadows/build nest in side of ship/offers to fence goods)
3. Camp of 1d4  Leeches, Giant (suck dry/just a little taste/attack next encounter)
4. Wing of 2d8 Griffons (attack sails/flyby salute/mutely request medical aid)
5. 1d2 Octopodes, Giant. (drag sailors under/get caught in the rudder/trade shipwreck doubloons for treats)
6. Outfit of 1d4*10 Brigands. For every 20, there is an additional ship. (rob/seeking repairs/pay to say nothing of this to port authorities)

Stinking Enchanted Swamp
1. Bushel of 2d6 Ogres (crack skulls/scare off/invite to horrid supper)
2. Infection of 1d4 Yellow Moulds (inconvenient place/allow people to pass with care/reveals secret cache)
3. Jolt of 5d4 Bugbears (rough up/practical joke/invite to bawdy night out)
4. Span of 2d6 Mules (stubbornly rebuff/look on in dismay/cry out for help with human voices)
5. Slip of 1d4*10 Pixies (slit/lead astray/lead to boon)
6. Haunting of 1d6 Wraiths (scare away/twisted warning/offer boon for proper burial)

Moral Test Bayou
1. Fancy of 1d4 Chimerae (exemplify wickedness/exemplify diffidence/exemplify virtue)
2. Market of 6d10 Goblins. 1-in-5 chance they ride wolves. (force to eat unwholesome fruits/sell unwholesome fruits/trade like reasonable people)
3. Pack of 1d8 Unicorns (impale/flee/defend)
4. Camp of 1d4 Leeches, Giant (suck virtue/attacking peasants/offer to suck vices away)
5. Shiver of 3d6 Sharks, bull (circle before attack/follow waiting for wound/propound the virtue of wrath)
6. Empire of 1d4 Owl Bears (drive off/bicker among themselves/offer wisdom)

Overgrown Pilgrimage Battlegrounds
1. Churchyard of 1d6 Treants (rebuff intruders/demand test of conviction/enforce sanctuary)
2. Scandal of 2d4 Harpies (ruin/vandalize/repent)
3. Grey Ooze (ambush/attempt to recreate a saint’s statue/perform rites)
4. Wing of 2d8 Griffons (do battle/report troop movements centuries out of date/ask for help in their confusion)
5. Squad of 2d6 Veterans. (opposed faith/mercenaries/theologically aligned)
6. Sleuth of 3d10 Berserkers (non-consensual tests of strength/share bread with allies in faith/seek recruits)

Lake Canal Frontier
1. 1d2 Octopodes, Giant (abduct across water/offer wrestling match/escort)
2. Crew of 5d8 Dwarves (boss around/survey area for construction/share information near build site)
3. Band of 1d4*10 Brigands. Half are mounted. (rob/”invite” to expensive meal in the woods/gift arms and burglarious tools)
4. Pack of 1d6 Blink Dogs (presage accidents/beg food/accompany until they help with a disaster)
5. Dragon, sea (terrorize and steal/demand toll to continue/offer aid in destroying pesky monsters)
6. Shrieking of 1d8 Spectres (drive off/vandalize/request reuniting with living descendants)

Uncovered Swamp Ruins
1. Invisible Stalker (homicidal rage/guards a treasure/just really needs a friend right now)
2. Swarm of 2d6 Robber Flies (Bite with sleeping poison/buzz in warning/dance for onlookers)
3. Cell of 1d12 Mediums (ineptly attempt capture or enticement/perform baleful summoning/perform amusing tricks)
4. Elemental, lesser. Water elemental. (rage for ancient wrongs/weep for ancient wrongs/aid those who are still innocent)
5. Herd of 1d12 Pegasi (territorially defend area/struggle in the mire/offer ride)
6. Drove of 1d4 Gorgons (buck/graze on poison/follow out of domestic instinct)

Isolated Taiga March
1. Sleuth of 1d4 Bears, black (pursue ravenous hunger/laze about sleepily/show where to find sap)
2. Golem, wood (scare off/wandering among friends, offended by firewood/offer shelter)
3. Colony of 1d6 Vampires (charm and drain/invite to leaning wooden edifice/offer office and sign of protection)
4. Copse of 1d6 Dryads. Coniferous (entice into tree/hide despite evidence of activity/party hearty)
5. Herd of 2d8 Mastodons (stampede/pass warily/leave 1d2 valuable tusks)
6. Depot of 3d10 Bandits. Technically empowered by foreign power (press-gang/pay for supplies/invite to merriment and conspiracy)