World Bonuses, Penalties, and Cover
The action hardly happens in a featureless void. Craggy roads, chandeliers of suspect quality, and figures reaching out from the mists for fresh blood can all greatly shape the way you move through the world.
World benefits and world penalties are objects, obstacles, and field conditions in the immediate area. They might provide you with bonuses, or can slow you down and provide another source of danger.
Difficult Terrain
One of the most common forms of world penalties is difficult terrain. Anything from dense bramble, precarious steps, or tenacious mud can slow you down from your normal movement speed.
Every foot of movement you take within difficult terrain costs 1 extra foot. Multiple hazards that would cause difficult terrain in a space do not stack. However, additional conditions that increase the cost of movement (such as crawling while prone ) stack with difficult terrain.
Cover
A common world benefit presents cover for participants that stumble on it. Larger obstacles such as trees and stone walls can help to keep creatures out of sight and out of harm's way.
Cover provides you with protection from attacks and effects that originate on the other side of it. There are three degrees of cover: half, three-quarters, and total cover. If you are behind multiple sources of cover, you only gain the benefits from the most protective source of cover.
Half cover is provided by obstacles that block at least half of your body, such as a tree trunk or another creature. Half cover provides you with a +2 bonus to AC, saving throws , and ability checks made to hide.
Three-quarters cover obscures three-quarters of your body, like an arrow slit or a castle wall. It provides you with a +5 bonus to AC, saving throws , and ability checks made to hide.
Total cover keeps you completely concealed from the other side. You cannot be targeted directly by attacks , spells , or ability checks, although spells that target an area of effect and checks to search the area might still reach you.