"Environmental damage" is any time a character takes damage that wasn't caused by a direct, intentional force. When a mage casts a spell at you, that's direct and intentional. If the mage's spell misses you but knocks out a load-bearing beam that drops the ceiling on you both, the falling ceiling is environmental. The same thing is true if someone falls to jump across a chasm and hits the ground below, hard. Or if someone is caught in an avalanche, or breathing the toxic air in a sealed crypt.
But what Stats do you give a falling ceiling or an avalanche to determine the damage it deals, and how do you determine what stat the PCs use to resist getting crushed, buried or suffocated?
Resisting Environmental Damage
The simplest way to calculate Environmental Damage (if you don't want to try to figure out the relative Strength stat for gravity) is to instead pick a base damage for the affected characters to roll against.
Let's take our falling ceiling example. Let's say we set the base damage for a falling ceiling at 15 PP. That's the damage a PC standing under that roof would take unless they can dodge or resist the damage.
Then, have the PC roll the appropriate stat(s) against a difficulty of 1. Any PP they produce are subtracted from the base damage, and if anything remains, that's the damage the PC takes. If they produce as many or more PP as the base damage, they avoided or resisted taking any damage at all.
This formula works with either single-trait rulings (someone rolling CON to resist the effects of toxic air in a sealed crypt, or rolling END to sump a fall from a high height) or two-trait rulings (rolling DEX and END to avoid and resist damage from our falling ceiling). In both cases, the difficulty is 1, and any PP generated subtracts from the base damage you set.
Determining Base Damage
All that remains is to set the appropriate base damage for the environmental effect.
It's important to keep in mind that, most of the time, a character will be resisting with a stat only. Most combat and magic skills aren't directly applicable to resisting environmental damage (although many mages could chose to try and conjure a shield instead rather than simply rolling END). So understand the scale you're working from.
If your average PC is bringing a stat of 25 to the situation, then 80% of the time they'll only sump 4-5 damage from an environmental effect. Even someone with a high stat and skill who brings an 80 might to the situation is only sumping 15 damage 80% of the time. Use that to gauge the best base damage to set based on the situation, so you know what to expect.
Base damage most of the time for environmental effects should be 10. Anything above 10, assume that most of your PCs will be taking the difference. In our falling ceiling example, at 15 PP, you can expect most of the characters to take 5-10 damage. Some exceptional effects (being caught in a lava avalanche, teleporting to the bottom of the ocean by mistake, etc) will go beyond that, but the majority should fall within the 5-15 range.
For specific examples, refer to our Environmental Damage Base Damage Chart
Special Cases - Falling and Space
Falling damage follows the same rules, with one exception - it scales based on how far the character is falling. Set your base damage to how many feet the character has fallen when they land (a 20-foot fall has 20 PP of base damage). That may seem extreme, but in the real world, a fall of over 30 feet is rarely survivable. In IC terms, that would only knock out most characters, if that (and if they absorbed none of the damage at all), so we're actually allowing for falls from higher heights, because it's a game :)
Additionally, we currently have exactly one environmental situation that follows separate rules than these - space. They're listed at the bottom of the Monkeys in Space wiki page.
Normally applicable only to Sirian, the space rules handle round-by-round rulings for anyone suddenly finding themselves in a vacuum. If you feel inclined, you can use similar rules for handling situations like drowning or deep ocean environments (extreme pressure, extreme cold, lack of air) or toxic environments (holding breath, dealing with corrosive effects, etc).
Armor and Environmental Damage
The damage reduction from Armor and Shields does NOT protect or absorb Environmental Damage from sources like natural fire, extreme cold, noxious gas, etc.
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