LP Labs: Let’s Make Some Poisons 4

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This is the first article in a category I’m calling “LP Labs.” This category will hold our articles which contain little homebrew ideas that are not part of a larger project.

So, I’m getting ready to launch into a brand new campaign that I’m DMing for Polyhedral Complex (October 23rd is going to be our kick-off date, 1930 EST on Twitch). One of my players came to me this morning and asked if he could change from being a Barbarian to being a Rogue. “Sure man, we haven’t even started yet, so no problem,” was my immediate reply. Then he asked this:

Question about poisons. They have a list of sample poisons and I was wondering if we could expand upon that and make custom ones.

To which my immediate reply was “Oh shit yeah!”

Poisoning has always had a bit of a weird history in D&D. Back in the bad ol’ days of 1e, poisoning was nearly always lethal unless you saved. Indeed, the AD&D Player’s Handbook had a whole section which basically said, “Putting poison on a weapon shouldn’t be allowed because it’s too good and the game wouldn’t be challenging.” That’s because, back then, you either saved from poison, or died. There was even a spell, Slow Poison, which had the sole purpose of giving you some extra time to cure that shit before you died. And let me be perfectly clear: this was not “take a bunch of damage.” This was “dead.”


Since then, the fantasy trope of “poisoning a weapon” has been incorporated more and more. However, for some reason, it is often under utilized or straight up ignored. Likely, this is because it’s yet another thing to deal with, and the payoff isn’t super great. Waste an action to add 1d4 damage to my weapons for a bit? Wheeee! That’s certainly how it feels in 5e, where, for 100gp, we can apply a vial of poison to a weapon which adds 1d4 damage for 1 minute. Well, assuming the target doesn’t pass a DC 10 CON save. Not like that’d ever happen…

If you want something more potent, there are a few sample poisons the core rules offer:

from Roll20

Holy hell, 150 gp for the cheapest one on that list, and I have to get the hapless victim to eat/drink it? The first one I can put on a weapon costs 200 gp (Serpent Venom) and I can’t even make that myself, I have to go find a snake, kill it, harvest its glands. Oddly enough, there are rules in the DMG to do exactly that, yet the rules are fairly sparse on coming up with custom poisons and allowing players to make them. Fine, let’s do it ourselves.

System of a Dose

Ok, so what I want to do is come up with a basic system for poisons and their value. We’ll cover ways to make them more interesting and useful for players afterwards, but let’s take care of the basic framework first. What I’m going to do is assign each poison a set of “Efficacy Points (EP).” Basically, EP sums up into a neat little number how useful a poison is to an adventurer. Now, notice I said “to an adventurer” there. That’s an important distinction, because a nobleman is going to far prefer a poison which he can surreptitiously slip into a drink rather than something he has to wipe all over a blade and then out-and-out stab someone with. The former is neat and tidy, the latter is messy and attention-seeking. However, it’s exactly the opposite for an adventurer. So, this EP system will be from an adventurer’s perspective.

Step One: Delivery

Before we can decide what the poison actually does, we need to determine how one actually delivers the poison. 5e provides 4 vectors for delivery:

  • Contact This poison can mess up your day even if it’s just on a doorknob you happen to touch. It has to touch skin, though, so a tough pull in combat. 0 EP
  • Ingested The targets needs this one to actually go in their face and down their throat. Tricky vector for mid-combat. -1 EP
  • Inhaled This vector is useful for poison gas vials and whatnot. Neat! 2 EP
  • Injury This one’s for weapons, and will be the adventurer’s bread-and-butter. 1 EP

Step Two: Duration of “Poisoned”

There is a condition in 5e called “poisoned” which is, to be frank, pretty devastating. Disadvantage on all attack rolls and ability rolls is nasty, especially for something that can be fairly easy to get. Again, we’re looking at this from the perspective of an adventurer, where this is very important. It also means that, beyond an hour, any amount of time is just as useful.

Note: Any lingering effects (damage per round, other conditions, etc.) are also tied to the “Poisoned” condition. Once it is removed, the poison’s other effects are also removed.

  • Does not apply this condition 0 EP
  • 1 to 3 rounds 1 EP
  • 4 rounds to 1 minute 2 EP
  • 2 minutes to 1 hour 3 EP
  • 1 hour+ 4 EP

Step Three: Save Potential

Ok, the target definitely gets a save, but how hard of one? How often?

  • DC 10 0 EP
  • +2 DC 1 EP (repeat as needed)
  • Save ability other than CON 1 EP
  • Repeat every round 0 EP
  • Never repeat 2 EP

Step Four: Damage

Does this poison hurt? Cool. If it doesn’t do any damage, skip this step.

  • 1d4 1 EP (each)
  • 1d6 2 EP (each)
  • 1d8 3 EP (each)
  • 1d10 4 EP (each)
  • 1d12 5 EP (each)
  • Damage applied only once? 0 EP
  • Damage applied every round? 2 EP
  • Save negates damage completely? -1 EP

Step Five: Other Nasties

Sometimes (often), poisons do other crazy things which are way more important than the damage. These effects last for as long as the target has the “Poisoned” condition from this poison.

  • Minor effects 1 EP
    • Deaf
    • Blind
    • Truth
    • 2 level Exhaustion (for duration)
  • Major effects 3 EP
    • 3 levels Exhaustion (for duration)
    • Frightened
    • Uncoscious (wakes when hit)
    • Charmed
  • Epic effects 6 EP
    • Paralyzed
    • 4 levels Exhaustion (for duration)
    • Incapacitated
    • Stunned

Okay, so this is the basic framework, and it covers all of the sample poisons. There will likely be neat little customization options that can be added (like a poison that can be applied to more than 3 arrows, or lasts 10 minutes on a weapon instead of 1), but that’s for later refinement.

Cost Cost Cost

Now, let’s take a look at all the samples and how they stack up:

  • Basic Poison 100g – 1 EP
  • Assassins Blood 150g – 8 EP
  • Burnt Othur Fumes 500g – 12 EP
  • Crawler Mucus – 200g 10 EP
  • Drow Poison – 200g 11 EP
  • Essence of Ether – 300g 14 EP
  • Malice – 250g 11 EP
  • Midnight Tears – 1,500g 21 EP
  • Oil of Taggit – 400g 11 EP
  • Pale Tincture – Special (this poison is NUTS)
  • Purple Worm Poison – 2,000g 30 EP
  • Serpent Venom – 200g 8 EP
  • Torpor – 600g 12 EP
  • Truth Serum – 150g 4 EP
  • Wyvern Poison – 1,200g 18 EP

As we can see here, there is some variance in the cost of a poison vs. its EP value. I doubt WotC came up with a formula for poisons (if they had, they would have given it to us in the DMG), so it’s probably because the poisons were kind of “top of the head” balanced for their effects, then given a rough gold estimate. However, we can generally see that the single-digit EP poisons are under 200, the low teens are under 1000, and then we go up from there. Purple Worm Poison is crazy potent for just 2k gold, so I’m not sure what the thought process there was.

However, for this system to make any kind of sense, we need to put actual gold values to the EP so that DMs and players can know what these things are worth. So, let’s just throw out a simple formula, and call it a day:

Cost of poison = 100 + (EP^2.3)

Yeah, it’s not ideal (to the power of 2.3? Ugh), but it scales fairly well, and pushes that Purple Worm insanity into the 2.5k range.

Why is the cost important? For crafting, of course. Really, poisons are generally going to be wildly expensive to buy, because they’re generally illegal (except in Tamriel for some odd reason). However, when crafting something, you don’t go based on its market value, but its regular cost. Further, some poisons require truly obscure or exotic ingredients (there’s that Purple Worm again), which can drive the market value way up, but the base cost isn’t all that extravagant. Sure, as long as you have Crawler Mucus, it’s easy enough to make a poison out of it.

I have more on this, but we’re already bumping 1400 words, so I’m calling it here. Think I should add some stuff? Think this is totally bonk? Totally awesome? Shoot me an email and let me know: contact@legendarypants.net.


4 thoughts on “LP Labs: Let’s Make Some Poisons

  • WP

    This is awesome! I doubt my DM will go for it, because he seems to be of the opinion that – unless you’re a full caster – you don’t get status-effect-inducing abilities “for free” (even though there’s an obvious cost to these things…).

    That said, I’d love to hear more! Maybe do a comparison of spell effects and the spell scroll cost vs. potential poison effects and the 100+EP^2.3 cost curve. Something so players like me can browbeat their DMs into accepting this awesome system by countering their every argument =)

    • Matthew Stanford
      Matthew Stanford Post author

      I’ll definitely mention that in the part 2.

      If you want a quick win for a DM argument, point out that spell casting is free whereas this costs hundreds of gold per dose.

      DMs always love a good gold sink.

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