On Earth there are many different types of poisons. Animal poisons are usually injected and can cause anything from pain and irritation to rotting flesh, organ damage, anaphylactic shock, and even death. Plants and fungi can be irritating and painful to the touch, like poison ivy, poison oak, and stinging nettle, or even more harmful and even deadly if swallowed, like hemlock, nightshade, oleander, blackcap mushrooms, and poinsettia. Chemicals like arsenic, chlorine, strychnine, and many others created by man as well as naturally existing have a variety of effects from nausea to death, often based on how much is breathed or consumed. And then, of course, humans have weaponized any and all of these types of poisons to coat their weapons or contaminate the ventilation systems or water supplies of rival companies, factions, or cities.

There is no way to really cover each and every one of these in a specific way without making for an incredibly complicated game, so we'll create simple rules for poison and let the GM increase or decrease the number of attack dice and a multiplicative effect on residual dice to represent how deadly the poison is considered.

Attacks using poison follow the general rules for Area of Effect, Size, and Duration and generally come in two varieties: ones that require a person be struck first and those for which a character would merely have to breathe or consume to receive the effects.

For breathable or consumable poisons, the poison attack would be handled by itself as an attack vs Poison or Disease. All successes would cause damage and residual effects would be handled as described below.

For poisons requiring that a person be struck, at least one point of force damage, usually piercing damage, would have to occur first. Then the character would roll a second set of defense dice against the poison. A viper might, for example, only roll four attack dice against piercing because their bite hurts but isn't necessarily deadly except to tiny creatures, but if any of those dice are successful, they might then roll eight attack dice against poison or disease to represent how deadly the GM thinks the poison actually is. And then a 2x or 3x multiplier in residual effects after that, also to represent the deadliness of the poison.

Additionally anyone affected by at least one point of poison damage is considered poisoned. A poisoned character automatically rolls at the beginning of each turn against an equal amount of dice to the amount of damage they took the previous round times the multiplier representative of the toxicity of the poison. This continues each round until the defender beats all attacking dice or they are cured, either magically or medicinally. If multiple poison attacks are successful, residual effects in later rounds are defended against grouped together.

In the unlikely event that multiple types of poison are used with varied multipliers, the GM averages the multipliers to come up with a new multiplier and multiplies using that, round the dice upward to the nearest integer.

Example: John the Barbarian is hit with a poison bolt. His poison defense is three. The attacker has five dice. The rolls are 5, 3, 6, 1, 1 vs 6, 6, 2, which is 6 vs 6, 5 vs 6, 3 vs 2, and two 1’s that aren’t defended. John takes 3 points of damage. The next round John has to defend against three dice, the ones he couldn’t defend against the first round, times the multiplicative effect of the poison.

Let's say this isn't a very virulent poison and has a x1 multiplier on it. 3×1 is still just three dice. So he would roll against just 3 dice the next round.

But that doesn't prevent the attacker from attacking again. With poison… again!

John would get a second poison roll against this new poison attack, but if he has one remaining die from the first attack and one remaining die from this second attack, the next round he would have one roll against two dice of residual damage, multiplied by the potency multiplier, which, lucky for John, is just x1.

If instead, the assassin coated his second bolt with a x3 far more deadly potency poison, the average of the potencies would result in an x2 multiplier, meaning that poor John would have to roll against 2 dice X 2 potency dice, which would be 4 poison dice the next round.

And hopefully for John, the assassin has now run out of poison!