Tuesday, 30 April 2019

Keystone Species Encounter Table

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This one of those "thinking aloud"post where I had an idea for something and see what it looks like when I write it out.
Which hopefully results in something usable , salvage , inspiring or at the very least interesting.

This idea is building an areas encounter table around a single species , in order to make it feel more alive and dynamic , and allow more forewarning to happen about the more dangerous encounters.

So you decide on a keystone "species" (though this can be any thing "ëncountable") and think how it would effect everything else.

What is a keystone species? Let me just copy/paste from wiki here:

"A classic keystone species is a predator that prevents a particular herbivorous species from eliminating dominant plant species. If prey numbers are low, keystone predators can be even less abundant and still be effective. Yet without the predators, the herbivorous prey would explode in numbers, wipe out the dominant plants, and dramatically alter the character of the ecosystem."

 A keystone species doesn't have to be a predator but we'll start with one because it's the easiest to d&d.

So let's take the Hydra-Moray from  the "Ramanan Sivaranjan Excellence in Gaming Best God Damn Book of 2015"award winning book Fire On The Velvet Horizon.

It's one of the simplest monsters in there, a hydra of eels , so it will do nicely.

Let's have it live a mangroove, because they are under used biomes. Mangroves are great because you have all kinds of water monsters there but have the party  still basically on land.

Real life mangroves are kind of a nightmare to travel on foot, the footing is treacherous, sharp protrudings from the mangrove roots ,  deep sucking mud and biting insects.

But for our purposes I'll say there's more reliable ground than there actually is.

What does a Hydra Moray eat? Basically everything.  It will eat the mussels and other shellfish , it will eat fish, it will eat alligators , it will will eat too slow climbers and flyers.

So I'm think it's unlikely to have another large predator here unless its swam in from further away.

However smaller & faster and/or more versatile predator/scavengers seem plausible (also I could always have something with some unusual property allowing its survival.)

So let's have some kind of tree climbing Hyena-Otter.

Like the Amazonian giant otter but hunting in packs and a rapid climber . They will scavenge, eat shellfish, chase smaller or weaker Hydra Moray away from kills, snip off stray bits of a meal or even a head, or just finish off the remains.

They will retreat into the tree tops when endangered and make large messy nests there.

Okay now for hapless prey animal.  Gibbons.The Bald-screamer gibbon which I'm making up , it's nearly hairless and has a look of constant fear on its face. It eats leaves, fruit , bark and occasional shellfish.
They will get eaten in the water and they will get eaten in the trees. They have the long limbed graceful  swinging in trees but in the water they have an absurd looking butterfly stroke .

They will squirt big jets of blinding green shit loaded with herbal toxins from their diet if disturbed, while fleeing and hooting.

This hooting will attract attention of the Otters but not the Moray.

Now I got 3 beasts lets build an encounter table.

I don't have a clear system about how I do these numbers , but generally I treat a hex/ turn of traveling like doing a room in a dungeon so I like a 3/3/3 of Definite threat, possible threat, environmental.
Definite Threat is something that is very likely to result in harm unless action is taken, a possible threat will result in harm only in specific situations or fuckery, and environmental is traces of the threat , clues, and resources.

Then with those categories , where needed, a third are unluckier than usual and a third  are luckier.

That's my guidelines here anyway. I'm still not 100% in these numbers and I actually deviated from it when making the below table. ヽ(。_°)ノ
Note that a lot of traditional encounter chances are created with them as a counter /penalty /risk to taking too much time/ covering distance , while I use them as a "what are we doing this session" generator.

Any Large amount of Noise (i.e Gibbons) , or blood in the water ,will trigger another encounter roll , only using results relating to Hydras or Otters

Definite Threats
1. A younger , wounded, or depleted Hydra Moray. It has less than normal heads (1d4+2) , will follow at a distance and attack if approached , the party seems weak, or there's a lot of blood in the water. It will settle for at least a dogs worth of meat.
2. A healthy Adult moray will become aware of the party and start slowly swimming towards them , waiting for the best moment to strike. It will want at least 2 adults worth of food , and if it incapacitates one while the rest of the party flee , it will stash the downed one under a root mass and continue 
 3.Adult Moray about to eat or currently eating a shark or crocodile . Will defend its meal against others. Roll again to see if anything else shows .
4. 1d4 younger Otters. Will follow just out of reach , both in the water or tree branches looking cute. Will attempt to snatch and flee with food or small animals , and attack isolated injured individuals
5. Standard pack of otters , 5+1d6 of them. Lolling about in branches and eating shellfish.  Will attack a weak looking party, try and chase off other packs or smaller morays from a kill. If the next encounter triggers an encounter roll , this pack will show up.
 6. Otter Nest. Looks kind of like a bunch of flotsam jammed in a tree. 2d8 pups present. 1d4 otters present that will chase off anyone getting close. Another 2d6 will show up if prolonged combat or aggravation happens. The pups are worth a lot for their fur, and use as  hunting./guard animal. 
The nest also might have rings or jewellery from limbs or heads brought back here for the pups to eat.
 7. Shark
9-15: Gibbons up trees . Will freak out if disturbed, shitting jets of blinding spray and making a lot of noise.
16 A corpse up a tree. Legs eaten off, rest of body stripped of bone. Some salvagable equipment
17. Battered down smaller trees
18. Submerged corpse under a root mass, with a single limb rising up. Hydra Moray that stashed it was driven out of the area.
19. Crocodile corpse caught up in emerging root mass, being picked clean by crabs
20. Knocked over Otter nest , ripped open.  Human limb and gibbon bones through the compacted nest surface of fur, plant material , and feces. Some jewellery.

Next post , if my or your interest continues , will have one the following goals:

>Make a  way simpler version of this.

>Show an example with lots more variety

><Maybe do one with something other than an alpha predator

>Or even building it around something that isn't part of the food chain (directly) like rogue golems, or wandering bands of undead


  1. I've always thought that really intentional ecological design could be cool for encounter and bestiary building. That being said, I think it could be interesting to go the other way, have a random roll table of environments, apex/keystone predators, maybe some secondary predators, scavengers, or prey animals, and then try to build out an underlying logic for how these things could come together in a semi-logical, semi-coherent way. I actually built a rough version of this a long time ago on my blog. Anyway, this is very cool and I'll be interested to see where this goes!

  2. I like this a lot. It’s an evocative little environment you’ve set up there. I think this would help with my general lack of ability to imagine ecosystems.

  3. Great stuff! Mangroves are under appreciated...

  4. Thought provoking! I'd very much like to see more of these. But I concur with Max, having random events and then having to justify them sometimes ends up being more interactive than a "logical" setup. Unless you have an area that is frequently being explored, the logic of the place won't become apparent. Then again, it's also a tool for the DM to know what kind of things make sense to show up... lots to think about here!

    1. Yeah the top down approach vs the bottom up approach.
      And it is a danger getting way too logical when building an encounter table that is only going to be used 1-3 times. However this example above by having very few occupants and each encounter connected with another means that the emergent interconnectness should be sure to happen.

      An easier approach than this keystone marlacky is just to make each encounter reference another encounter somehow though