D&D 5e - Questionable Arcana - Crafting: The Poisoner's Kit
I've finally seen my modifications to the 5e crafting system in action, and I must say I've been very happy with the results. However, in the course of explaining its mechanics to my players, I noticed some areas that still needed a little fine-tuning. In an attempt to flesh out the aforementioned crafting system, I'm going to do a series of articles featuring specifics from each kit. The first kit in the Questionable Arcana Crafting Series is going to be the Poisoner's Kit.
Before we begin, it's worth noting that the primary purpose of this article isn't to layer a bunch of new mechanics on top of what we already have. Don't get me wrong; there will certainly be additional mechanics and clarifications, but the idea is to go through a couple of crafting "case studies", helping other DMs apply the new crafting system manage some of the issues or loopholes you could encounter.
If nothing else, think of this series as something to reference when you need inspiration for uses of the system.
First, A Quick Overview of the Rules As Written (RaW)
The existing rules for extracting and using poisons harvested from creatures are pretty solid. You kill the creature and attempt a DC 20 Nature Check to harvest the poison, with a successful check yielding either a one-use poison you can apply to a blade for one minute or three pieces of ammunition. A failed check makes it impossible to harvest the poison, and a failure by 5 or more subjects the player to the poison. The effect of the poison is based on the creature's description, matching the effect applied after the target makes its savings throw.
If I were only allowing poisons harvested from creatures, this would be sufficient. It is simple, effective, and doesn't leave too much room for abuse (more on that later). However, the Rogue in my 5e campaign made it his personal goal to learn how to craft Floral Poisons. Being the generous DM that I am, I decided to do what I do best: run through dozens of hypothetical situations with Truck until we produced some concrete rules.
The Problem with Floral Poisons
5th edition doesn't detail many rules regarding plants, much less how to turn those plants into poisons. It doesn't even attempt to address the implications of a player who decides to try and create his own Brownroot farm in hopes of mass producing a furious bowel poison.
The gold-based crafting system works beautifully when all components are being purchased on the market. For example, explaining the crafting process of a garden-variety poison in the Adventuring Gear section of The Player's Handbook is easy enough. Essentially, you're trying to create a stable poison out of various household ingredients, which requires some pricey objects if you're buying in a normal market.
But what happens when a player creates the aforementioned Brownroot farm, enabling him or her to procure a massive glut of the poison's active ingredient? With the cost factor largely removed, things could quickly spiral out of control, ending with an entire party permanently toting poisoned short swords with overpowered effects!
The Solution to Floral Poisons
Rather than creating arbitrary limits on how much of a given herb you can harvest, I realized the cost mechanic could still be applied in this situation. As far as I know, there are no magical poisons in The Dungeon Masters Guide, so any plant-harvested poison can be considered a mundane item. Mundane items in both my home-brewed system and RaW have a base gold cost of 50% of the value of the item being created.
In this case, the best solution is to simply alter where the costs lie in the poison crafting process. The majority of plants the DM introduces as "craftable" reagents can't just be mashed up and applied to a weapon. Creating a stable poison requires a variety of chemicals and a great deal of steeping time to extract the poisonous effects from the plants. So even with a Brownroot stockpile, the majority of the costs remain tied up in other ingredients. With this modification, you're now able to apply a gold-based crafting process to plant-based poison formulas.
Your players may protest and point to real life examples of plants which can be immediately applied to a weapon. You can fold your arms and say they don't exist in your world, but there's no reason these simpler floral poisons can't coexist with the more complex. The party may occasionally find these "instant" poisons in the wild, but I recommend restricting the environments they grown in to avoid abuse. For example, a hypothetical Firevein plant capable of dealing 1d6 fire + 1d6 poison damage on injury can only be found on the slopes of an active volcano.
As stated above, RaW for extracting poisons from creatures are effective. A DC 20 Nature check, modified by your Poisoner's Kit proficiency, is very reasonable and also scales into later levels. However, there are a couple of loopholes the DM should be aware of.
The first and most obvious source of abuse is harvesting poison from a player-owned pet, companion, or familiar. Although most creatures eligible for those roles have fairly weak poisons, some notable exceptions could cause major power creep late into the campaign.
Let's say a Wizard chooses a poisonous snake as a familiar. Because the familiar follows your orders without question, a clever player might try to milk the snake regularly to amass a poison stockpile. Rather than disallowing this behavior, I'd recommend some simple restrictions.
First and foremost, I'd limit the milking rate to once per long rest. Secondly, I'd require more than one milking to get enough venom for a useful poison. If harvesting a full venom sac from a dead creature typically yields one dose, a milked creature would logically have a lower yield. Lastly, a "milked" creature loses the ability to apply its poison in combat until it has taken a long rest. This is typically only an issue for home-brewed classes, such as the 5e Beastmaster, but these rules will help avoid power creep.
The last potential loophole I want to cover is a player who decides to go all Matt Damon and make a zoo to house all the snakes they find. This could hypothetically grow into a never-ending source of free poison, but it can once again be easily managed by the crafting cost formula.
Any large-scale creature milking operation would require staff to maintain the buildings and feed/milk the creatures. You'd likely also need a consistent supply of antivenom to prevent loss of life in the event of a staff member getting bitten. You can itemize this, but I'd recommend assigning a value to the poison being harvested and utilize crafting formulae. For example: 4 staff members proficient in the Poisoner's Kit harvesting poisonous snakes would milk 4d4*5+20 worth of venom per day from the snakes. If you assigned a value of 200 GP to the poison, it would take, on average, just under 3 days for the team to produce a unit of venom.
In the event that a character attempts to sell any poison on the market, I would limit the volume they are able to sell. I recommend using the RaW rules for selling a magic items on page 130 of The Dungeon Master's Guide.
Eventually a party member will get the brilliant idea of mixing all of the poisons they have in a jug and using it as a bottomless well of murder ink for their sword. To handle this situation, just dilute and combine the effects proportionally. If you take a poison that causes paralysis for 6 rounds and mix with with a poison that deals 2d6 damage hit, the product would be two units of poison that paralyze for 3 rounds, dealing 1d6 damage on hit.
Optional Rule: The process of mixing poisons causes the individual poisons to lose some of their potency. With this rule in effect, the example mixture above would only paralyze for 2 rounds and deal 1d4 damage on hit.
These rules and standards hopefully clear up a lot of the gray areas around poison crafting. We now have some concrete rules around creating plant-based poisons, and have addressed some of the major loopholes surrounding creature-based poisons. Much like the base crafting system, I did my best to avoid creating new reagent and rules tables. However, if your party has spent a bit too much time playing Stardew Valley and decides to open up the world's sketchiest family farm, this system can be expanded to accommodate their needs.