Third-Party Support: Binary Poison Compounds

“Third-Party Support” is a series where I take a look at a particular idea, rule, or other notable tidbit from a third-party d20 product (i.e. not from Wizards of the Coast or Paizo) that I think deserves more recognition. While I won’t rule out looking beyond d20-based RPGs, expect those to receive the bulk of the focus.

Knowledge (Current Events) #2

Knowledge (Current Events) was a series of free PDFs released by Ivory Goat Press. Each issue was only a few pages long, referencing topics from recent headlines that it offered d20 conversions for. The topics were eclectic, but delightfully so, as they covered things from unusual diseases to private space shuttles to man-eating leopards, showcasing how they could be used as inspiration for an interesting bit of mechanical crunch. It’s a shame that it seems to have disappeared from the Internet.

One item that I found particularly noteworthy came in issue #2, where it covered the use of a binary compound as part of a terror attack, using it as a basis for the following rules for “Binary Agents”:

The concept of binary weapons began to take shape in the 1980s. Binary weapons refer to the concept of developing nontoxic precursors that can be loaded in munitions. Once deployed, the precursors mix and develop the nerve agent.

As a concept, it is useful even in fantasy settings — the chief benefit being that the binary agents are not themselves toxic, and thus are not detected by spells and effects such as detect poison and neutralize poison. You can also poison someone with a half now, half later strategy.

For any poison listed in the SRD or MSRD, an equivalent poison can be produced in the form of a pair of binary agents. This increases the Craft (poisonmaking or chemical) DC by +5. The poison costs twice as much as usual to purchase or produce.

The usual 5% chance that a character has of exposting himself to the poison whenever he applies it to a weapon is reduced to 1%, as the precursors are safer to handle. However, he still risks poisoning himself on a natural 1 on an attack roll.

This strikes me as being one of those “how did no one else think of it?” ideas. Poisons are an under-powered threat in most d20 games – largely due to them being downgraded so that they tend to work as a mild debuff more than something which can put characters in serious peril – so anything that gives them a boost (ideally without requiring characters to take feats, levels in a prestige class, etc.) is a much-needed boost. Moreover, this particular augmentation is fairly intuitive: most gamers, I’d wager, know what binary poisons are.

The one critique I have with the above, from a rules standpoint, is that it doesn’t mention how long a single compound stays in the body. If you manage to get one of the two poison agents into someone, how much time do you have to slip them the other half before it’s no longer viable? There are probably various factors that go into it, but for ease of play, I’d recommend that a particular compound is broken down and metabolized out after 24 hours.

That final paragraph, about applying binary compounds to weapons, warrants further examination. As the article correctly notes, the major game use of using two-part poisons is that they’re not subject to poison-specific effects until they’re combined, typically in the body of the target. While that’s good for avoiding detection (or neutralizing agents applied ahead of time), it’s hard to see why anyone would do that in combat.

That portion of the rules seems to assume you’re using both compounds on a single weapon, hence the reduced chance of poisoning yourself during the application but the standard chance of doing so in subsequent combat. An alternative idea, if you’re fighting with two weapons (or a double weapon), is to put each agent on a different weapon. In that case, you still have the 5% chance of poisoning yourself, but it’s checked separately for each application (meaning that you’d only poison yourself if you failed both rolls, effectively a 0.25% chance). Likewise, you’d need to roll a natural 1 with each weapon while in combat in order to be at risk of poisoning yourself.

Finally, note that the above rules don’t change the delivery method of the compounds. A pair of binary agents that create a poison whose normal delivery method is ingestion must themselves be ingested to take effect; you can’t have one part be ingested and the other be delivered via an injury. (At the GM’s option, consider allowing the delivery method of one compound to be changed by increasing the Craft DC by an additional +5, cumulative with the increase for making the binary compound to begin with, and increasing the cost to triple what the poison normally goes for. Only one agent can be changed in this manner.)

Hopefully this will make poison a little more useful in your campaign.


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