Setting the Stage; Environment

 Source GM Core pg. 92

Primarily used during exploration, environment rules bring the locales your party travels through to life. You'll often be able to use common sense to adjudicate how environments work, but you'll need special rules for environments that really stand out.

Each of the environments presented in this section uses the terrain rules in different ways, so be sure to familiarize yourself with those rules before reading this section. Some environments refer to the rules for climate and natural disasters. Many places have the traits of multiple environments; a snow-covered mountain, for example, might use both the arctic and mountain environments. For environmental features with effects based on how tall or deep they are, those effects vary further based on a creature's size. For instance, a shallow bog for a Medium creature might be a deep bog for smaller creatures, and a deep bog for a Medium creature could be only a shallow bog for a larger creature (and so insignificant for a truly massive creature that it isn't even difficult terrain).

The Environmental Features table lists the features of various environments alphabetically for quick reference. The Proficiency DC Band entry indicates a range of appropriate simple DCs for that environmental feature while also providing a rough estimate of the danger or complexity of the feature.

Environmental Features

Feature	Proficiency DC Band
Airlocks	Untrained–trained
Atmosphere	-
Avalanches	Expert–legendary
Blizzards	-
Bogs	Untrained–trained
Catwalks	Untrained-trained
Canopies	Trained–master
Chasms	-
Collapses	Expert–legendary
Cosmic Radiation	Expert–legendary
Crowd	Trained–master
Currents	Trained–master
Decompression	Untrained–expert
Doors	-
Earthquakes	Trained–legendary
Elevators	-
Floods	Expert–legendary
Floors	Untrained–expert
Fog	-
Gravity	-
Gravity Wells	Trained–master
Ice	Trained–master
Lava	Expert–legendary
Magnetic Storm	Trained–master
Maintenance Tunnels	Untrained–expert
Precipitation	-
Psystorms	Expert–legendary
Radiation	-
Rooftops	Trained–master
Rubble	Untrained–expert
Sand	Untrained–expert
Sandstorms	Trained–master
Security	-
Sewers	-
Slopes	Untrained–trained
Snow	Untrained–expert
Stairs	Untrained–trained
Streets	Untrained–trained
Temperature	-
Tornados	Master–legendary
Trees	Untrained–master
Tsunamis	Master–legendary
Underwater Visibility	-
Vacuum	Untrained–trained
Volcanic Eruptions	Trained–legendary
Vortex	Expert–legendary
Walls	See Entry
Wildfires	Expert–legendary
Wind	Untrained–legendary

Environmental Damage

Some environmental features or natural disasters deal damage. Because the amount of damage can vary based on the specific circumstances, the rules for specific environments and natural disasters use damage categories to describe the damage, rather than exact numbers. Use the Environmental Damage table to determine damage from an environment or natural disaster. When determining the exact damage amount, use your best judgment based on the perceived level of danger.

Environmental Damage

Category	Damage
Minor	1d6–2d6
Moderate	4d6–6d6
Major	8d6–12d6
Massive	18d6–24d6

Terrain Rules

Environments frequently apply the rules for difficult terrain, greater difficult terrain, and hazardous terrain; these rules are summarized here.

Difficult terrain is any terrain that impedes movement, ranging from particularly rough or unstable surfaces to thick ground cover and countless other impediments. Moving into a square of difficult terrain (or moving 5 feet into or within an area of difficult terrain, if you're not using a grid) costs an extra 5 feet of movement. Moving into a square of greater difficult terrain instead costs 10 additional feet of movement. This additional cost isn't increased when moving diagonally. Creatures can't normally Step into difficult terrain.

Any movement creatures make while jumping ignores terrain that the creature is jumping over. Some abilities (such as flight or being incorporeal) allow creatures to avoid the movement reduction from some types of difficult terrain. Certain other abilities let creatures ignore difficult terrain while traveling on foot; such an ability also allows a creature to move through greater difficult terrain using the movement cost for difficult terrain, but unless the ability specifies otherwise, these abilities don't let creatures ignore greater difficult terrain.

Hazardous terrain damages creatures whenever they move through it. For instance, an acid pool, a corridor filled with molten slag, and a field of razor-sharp grass all constitute hazardous terrain. The amount and type of damage depend on the specific hazardous terrain.