Several types of Terrain can complicate your Movement by slowing you down, damaging you, or endangering you. Navigating these types of Terrain can be challenging, but it can also let you get an advantage over your foes.

Difficult Terrain

Difficult Terrain is any Terrain that impedes your 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 further when moving diagonally. You can’t Step into difficult Terrain.

Movement you make while jumping ignores the Terrain you’re jumping over. Some abilities (such as flight or being incorporeal) allow you to avoid the Movement reduction from some types of difficult Terrain.

Ignore Difficult Terrain

Certain abilities let you ignore difficult Terrain. If you can ignore difficult Terrain, you can also move through greater difficult Terrain at the extra Movement cost difficult Terrain normally imposes. An ability doesn’t let you entirely ignore greater difficult Terrain unless the ability specifies otherwise.

Hazardous Terrain

Hazardous Terrain damages you whenever you move through it. An acid pool and a pit of burning embers are both examples of hazardous Terrain. The amount and type of damage depend on the specific hazardous Terrain.

Narrow Surfaces

A narrow surface is so precariously thin that you need to Balance (see Acrobatics) or risk Falling. Even on a success, you are off-guard on a narrow surface. Each time you are hit by an Attack or fail a save on a narrow surface, you must succeed at a Reflex save (with the same DC as the Acrobatics check to Balance) or fall.

Uneven Ground

Uneven ground is an area unsteady enough that you need to Balance (see Acrobatics) or risk Falling prone and possibly injuring yourself, depending on the specifics of the uneven ground. You are off-guard on uneven ground. Each time you are hit by an Attack or fail a save on uneven ground, you must succeed at a Reflex save (with the same DC as the Acrobatics check to Balance) or fall prone.

Inclines

An incline is an area so steep that you need to Climb using the Athletics skill in order to progress upward. You’re off-guard when Climbing an incline.

Counting Movement

Lini decides to Stride. She has a Speed of 20 feet. She moves straight south, spending 5 feet of her Speed, then diagonally, spending another 5 feet. Her next diagonal move, because it’s her second diagonal of the turn, costs her 10 feet of Movement. She’s spent all 20 feet of her Speed and ends that Stride.

She Seeks, and something catches her eye to the northeast, so she decides to move toward it. However, the crumbled stone is difficult Terrain, so each square costs 5 more feet of Speed. She moves diagonally, spending 10 feet of Movement since this is an odd-numbered diagonal. She wants to move northeast again, but that would cost her 15 feet (10 feet for an even-numbered diagonal and 5 more for being difficult terrain). Instead, she decides to move directly north. This costs her 10 feet, so she’s used all 20 feet of her Speed and is out of Actions.