Friday, November 4, 2016

More Work on Poisons

If there is a part of the game that I wish I could wave a magic wand and eliminate, it is the use of poisons.  It isn't just that they're potentially super-powerful and able to unbalance a game in the extreme (as a many a DM has discovered if the poison rules don't effectively restrain an assassin from causing havoc), it is also that the actual detail involving poisons is exhaustive and extremely difficult to define.  Pliny the Elder describes over 7,000 different poisons, not to mention that anything has an LD50 level if enough is ingested.  Add to this the difficulty in defining the game effects of each kind of poison, it's specific lethality and consequent difficulty in manufacture and it gets even harder.  Of course, many incredibly deadly poisons are obviously very easy to make, if someone difficult to get someone to swallow willingly.

I have never liked the "save or die" option.  Poison simply doesn't affect people this way.  Many poisonings give plenty of time for people to get to the hospital and be saved, as we well know.  A person could easily spend a full year building up a very complicated system and set of rules to describe all the variable forms of poison, but for what?  A method of killing that is, frankly, somewhat dull compared to hacking people to death with a sword.

Still, poison has to exist so waving it away is not an option.  I've been steadily working up my own rules to deal with poison, partly on the wiki and partly in my head.  I've gone an extra step today (in keeping with

working on medicine/physician rules) to codify these rules further. I include part of the relevant wiki page below:

Poison Damage
Because poison attacks a creature from the inside, the amount of damage that is done is PER hit die or level, meaning that creatures with a high number of hit dice or levels are no safer from poisoning than creatures with less. A 1st level character, therefore, has as much chance of surviving being poisoned as a 10th level creature. This keeps in line with my rules defining biological units (see Hit Points). Most poisons range from a lethality of 1 to 10 points per hit die or level.

For example, a 5th level fighter and a 1st level fighter are each poisoned by a substance with a lethality of 5 hp/HD & Level. Because leveled creatures do possess 1 HD in addition to their levels (see Hit Dice), the 5th level will suffer 6 x 5 hp (30 damage) and 1st level will suffer 2 x 5hp (10 damage). In my game, an average 5th level NPC fighter would have 32 total hit points: a d8 (for mass, counting as the character's 1 HD) + 5d10. The 1st level NPC fighter would receive a d8 + 1d10, for 10 hit points. Each would suffer an amount of damage that would seriously threaten their survival, particularly if either had already suffered damage from other means. Any constitution bonus would greatly increase their chance of survival.

Likewise, we might compare an Indian elephant with 10 hit dice to the above, encountering the same poison. The elephant would suffer 50 total damage - but because the elephant weighs about 5 to 6 tons, it has an average of 9.5 hp/HD, or an average of 95 hit points.

Time of Effect

The damage caused by poison does not affect the victim all at once. To begin with, the poison must have time to enter the bloodstream and spread through the body: this alone will require 1 to 3 rounds, during which time the poison will cause no damage of any time. Once this time has passed, the actual damage caused by the poison is then a random roll from round to round, according the following formula:
  • Divide the total damage caused by the poison in half: this indicates the potential maximum effect (PME) of the poison per round.
  • Each round, roll a die equal to the PME and remove the damage that has been done from the initial total.
  • When the PME is less than the total damage remaining, reduce the PME to equal this remainder for each round that remains.
  • Continue to roll each round until all damage has been suffered.

For example, consider the 5th level fighter described above (we'll call him Ethan). We begin by rolling 1d3 to determine how long it takes the poison to take effect, with a result of 2. This will mean that Ethan begins to suffer damage in the 3rd round. We calculate the PME at half of 30 damage, a total of 15. In the 3rd round we roll 1-15 to see the damage and get the result of 4. This isn't enough to stun Ethan, so although he doesn't feel "well," he is able to continue acting freely.

With the 4th round we roll a 2 and Ethan's free action is still unaffected. In the 5th round, however, we roll an 8 and Ethan is now definitely stunned. He has taken a total of 14 hit points so far, so in the 6th round the PME is unchanged: Ethan takes another 6 damage and is in trouble. Thankfully, however, he is probably past the worst: because he has taken 20 damage so far, the PME is reduced to 10 points. In the 7th round we roll 1-10 and Ethan suffers another 5 damage. We reduce the PME again and in the 8th round, we roll 1-5 and Ethan suffers 4 more damage. This leaves only 1 left, so that in the 9th round he takes this last damage and the poison has run its course.

While this does impose a more complicated procedure where calculating the damage done by poison, it does increase the game's tension where it comes to the character being unsure of how bad the poison really is. There is also time to give aid, allaying the damage caused by the poison with spell, potion or salve while it is happening, casting slow poison or neutralize poison if possible. Therefore, it is possible for a character to suffer more damage than initially possessed at the start of being poisoned. It also means that multiple poisonings (from monster attacks or consuming more than one dose before realizing the poisoning has occurred) could produce multiple PME rolls per round.

Saving throws against poisoning will reduce the total damage of the poison (and the PME as well) by 50%. Recognizing that a substance is poisoned before drinking is not considered part of a saving throw, but is a sage ability in its own right.

I intend to add this last (the ability to be able to smell/locate poison) to the assassin character's poison study ability.


AHunt said...

Those are very interesting. I don't like the rules as written but these seem pretty complicated. I'll have to give this some thought because I really like what you've done.

Alexis Smolensk said...

Sometimes, it is a lot harder to detail rules in print than it is to actually play them.

Ozymandias said...

A side effect of this rule seems to be that you have a relatively limited range for your poisons. In other words, given that PCs have, at most, 1d12 hit points per level, you basically have 12 levels of poisons to work with. Now, strictly speaking, that's not accurate: there can be poisons out there that deal 13+ damage per HD/level, but those would be considered (most likely) completely lethal. Arsenic, for example.

Then again, reducing some 7,000+ poisons to a range of 1-13 seems much more manageable. In that respect, I applaud these rules. A little complicated, as you say, but probably worth the extra effort for the extra tension and options you've created.

Alexis Smolensk said...


Going forward, I will probably adjust and tweak the existing rules, to make other sorts of poisons and to include poisons with higher kill potential. I will probably also come up with alternate means of reducing their effectiveness other than greatly increasing the saving throw option. It is a work in progress. Thank you for the praise, it is much appreciated.

Dennis Laffey said...

Interesting, I've also got poison in games on the mind, although real world stuff will keep me from working on it for a month or two.

The system you propose doesn't, as you say, look like it would be that complicated at the table. Once a character is poisoned, the DM needs to do a little math, but then from there it's pretty cut and dry how to have it affect the victim.

I'll keep this in mind as I rework how I want poisons to work in Chanbara. I want players of Shinobi characters to have access to poisons, but I don't want them to be the go-to, ultimate option, either.

I need to refresh myself on your damage system. If damage is over a certain amount for the round, it results in a 'stun' for the next round? That may be the thing I need to model the side-effects of poison (gagging, vomiting, diarrhea, crippling pain, etc.) in a simple way.


Spazalicious Chaos said...

Two things:
First, how do you plan to deal with poisons that are not intended to kill? There are toxins that paralyze, force unconsciousness, cause hallucinations, etc. Personally, when I need to bring in something alive, poison is my first go-to.
Second, dosage is a factor. Taking your example from above, I would recommend that your party use a larger dose for an elephant than a human fighter. Part of the assassins poison skill could be estimation of correct poison dosage for a victim, with underestimation having mitigated or no effect, while overestimation causing sooner onset and fatality, which may not have been the goal for someone who needed to take prisoners rather than corpses.

James said...

I was about to introduce poisons into my game, but hated the rules. This has given me a great starting point, thank you.

Alexis Smolensk said...


I will get around to giving descriptions for non-lethal poisons; these will be part of the alchemy/poison sage abilities, when I'm ready to expand them. Just now it isn't crucial to my campaign, so I'm letting these details rest on the shelf until a player expresses an interest in making poisons. I only wrote down the poison rules above because I was also working on a means for physicians to reduce the effects of poison.

Regarding dosage - the variable hit point damage per HD/Level described on the wiki link (I suspect you didn't hit the link just above the poison description) is based on weak dosages vs. strong dosages. Also, I'm basing the "dosage" as an approximate single swallow without easy detection or the amount that can be passed on by a poisoned blade. Obviously, if we can hold the victim down and keep pouring poison into them, everything is guaranteed to die.


I hope it can be of great use to you!

Baron Opal said...


I like the variable damage over time. The highs and lows coupled with knowledge that it will possibly extend through 3-8 rounds of damage gives good reason to have slow poison available. And, to find out if the local alchemist has any purgatives available.

For added complexity, you could make the mineral / metallic poisons do most of their damage up front, and then have lingering sequela. The organics would have a slower onset, and then with ever increasing damage up to a maximum as organs fail.

Is the damage simple dependent on agent? For large creatures you would logically need a larger dose. Divide the damage per die by the number of mass HD, maybe? That would give you a reason for otherwise unreasonably potent agents.

Nasty business, it is.

Alexis Smolensk said...


The reason the various poisons have names that are not names of poisons is because I don't want to get into the matter of deciding "what" the poison is: by using the names described on the wiki, I can be satisfied with what damage the poison causes, thus simplifying the game metric.

Effectively, there are a hundred combinations of different substances that could produce a vex, a distress or a woe.