Below is a list of rules related to the environment.
Walls, trees, creatures, and other obstacles can provide cover during
combat, making a target more difficult to harm. A target can benefit from
cover only when an attack or other effect originates on the opposite side
of the cover.
There are three degrees of cover. If a target is behind multiple sources
of cover, only the most protective degree of cover applies; the degrees
aren't added together. For example, if a target is behind a creature that
gives half cover and a tree trunk that gives three-quarters cover, the
target has three-quarters cover.
Half Cover. A target with half cover has a +2 bonus to AC and Dexterity saving throws. A target has half cover if an obstacle blocks at least half of its body. The obstacle might be a low wall, a large piece of furniture, a narrow tree trunk, or a creature, whether that creature is an enemy or a friend.
Three-Quarters Cover. A target with three-quarters cover has a +5 bonus to AC and Dexterity saving throws. A target has three-quarters cover if about three-quarters of it is covered by an obstacle. The obstacle might be a portcullis, an arrow slit, or a thick tree trunk.
Total Cover. A target with total cover can't be targeted directly by an attack or a spell, although some spells can reach such a target by including it in an area of effect. A target has total cover if it is completely concealed by an obstacle.
When you begin falling, you immediately fall 60 feet. While falling, you
drop another 180 feet at the start of each of your turns.
On impact, roll a
size die for every 10 feet you fell, to a
maximum of 20 dice. You take bludgeoning damage equal to their sum. Your
size determines your fall damage die, as shown in the table below. You
also land
prone, unless you avoid taking damage from the fall.
You can use your reaction to mitigate the damage from landing. When you
do so, make an Acrobatics check and reduce the fall damage by half the
result.
If you land in a creature's space, that creature must make a DC 10 Dexterity
saving throw. It can choose to fail. On a failed save, the fall damage is
split evenly between you and it.
The presence or absence of light in an environment creates three
categories of illumination: bright light, dim light, and darkness.
Bright Light. Bright light lets most creatures see normally. Even gloomy days provide bright light, as do torches, lanterns, fires, and other sources of illumination within a specific radius.
Dim Light. Dim light, also called shadows, creates a lightly
obscured area. An area of dim light is usually a boundary between a source of bright light, such as a torch, and surrounding darkness. The soft light of twilight and dawn also counts as dim light. A particularly brilliant full moon might bathe the land in dim light.
Darkness. Darkness creates a heavily obscured area. Characters face darkness outdoors at night (even most moonlit nights), within the confines of an unlit dungeon or a subterranean vault, or in an area of magical darkness.
When vision in an area is hindered by smoke, darkness, or a similar
phenomenon, the area is obscured. There are two degrees of obscurity.
Lightly Obscured. In a lightly obscured area, such as dim light, patchy fog, or moderate foliage, creatures have disadvantage on Wisdom (Perception) checks that rely on sight.
Heavily Obscured. A heavily obscured area, such as darkness, opaque fog, or dense foliage, blocks vision entirely. Nothing in that area can be seen.
Your size determines how much space you occupy. In combat, you normally occupy a square with a side length given by the Normal column of the Creature Sizes table below. This area, often refered to as "your space," represents the space you need to move and fight unhindered. You control your space, and can prevent other creatures within 1 size category of yourself from sharing it. Additionally, your space counts as both difficult terrain and half cover for all creatures other than yourself.
You do not have to occupy your normal amount of space. If you occupy less, whether by choice or by force, you suffer penalties.
Squeezing
Squeezing can reduce one or both side lengths of your space down to the value in the Squeezing column of the Creature Sizes table. You are slowed while squeezing.
Stuck
The value in the Stuck column of the Creature Sizes table is the minimum side length your area of control can have. If at least one side length of your area of control is between the "Stuck" and "Squeezing" values, you are stuck. While stuck, you are restrained. You can use a standard action to make a DC 10 Strength (Athletics) or Dexterity (Acrobatics) check. On a success, you are slowed instead of restrained until the end of the current turn.
Crushed
You can't willingly reduce a side length of your space to less than the value in the Stuck column of the Creature Sizes table. If you are forced to, you immediately take 1d10 bludgeoning damage for each inch your space's shorter side length subceeds your Stuck value, and you are crushed. You take this damage again at the end of each of your turns as long as you remain crushed. You are also stuck while crushed, and the DC to try to move increases by 1 for each inch your space's shorter side length subceeds your Stuck value.
Creature Sizes
|
| Minuscule | 1 ft. | 6 in. | 1 in. |
| Tiny | 2 ft. | 1 ft. | 6 in. |
| Small | 3 ft. | 2 ft. | 1 ft. |
| Medium | 5 ft. | 3 ft. | 2 ft. |
| Large | 10 ft. | 5 ft. | 3 ft. |
| Huge | 15 ft. | 10 ft. | 5 ft. |
| Gargantuan | 20 ft. | 15 ft. | 10 ft. |
Underwater, the following rules apply:
- Attack rolls with melee weapons have disadvantage, unless you have a swim speed.
- When making a ranged weapon attack, the long range becomes the normal range, and the normal range becomes 0 feet.
- Fire damage is halved.