Mountain

Mountain environments also include hills, which share many aspects of mountains, though not their more extreme features. The most common disasters here are avalanches.

Chasms

Chasms are natural pits, typically at least 20 feet long and clearly visible (barring mundane or magical efforts to conceal them). The main danger posed by a chasm is that characters must Long Jump to get across. Alternatively, characters can take the safer but slower route of Climbing down the near side of the chasm and then ascending the far side to get across.

Cliffs

Cliffs and rock walls require creatures to Climb to ascend or descend. Without extensive safety precautions, a critical failure can result in significant falling damage.

Rubble

Mountains often have extremely rocky areas or shifting, gravelly scree that makes for difficult terrain. Especially deep or pervasive rubble is uneven ground.

Environments make frequent use of the rules for difficult terrain, greater difficult terrain, and hazardous terrain, so those 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 is not 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 pit of burning embers, and a spike-filled passageway all constitute hazardous terrain. The amount and type of damage depend on the specific hazardous terrain.

Slopes

Slopes vary from the gentle rises of normal terrain to difficult terrain and inclines, depending on the angle of elevation. Moving down a slope is typically normal terrain, but characters might need to Climb up particularly steep slopes.

Undergrowth

Light undergrowth is common in mountains. It is difficult terrain and allows a character to Take Cover.