Common Hazards (PSR Supplement)

Consecrated terrain is imbued with holy power.

• Any undead on consecrated terrain has disadvantage on all saving throws.
• Any fiend that enters desecrated terrain on its turn, or starts its turn there, takes 1d6 radiant damage.

An attack with acid removes this effect from a 15-foot square of terrain centered on the point of attack.

If terrain becomes desecrated, it is no longer consecrated.

Desecrated terrain is tainted with the unholy.

• Any undead on desecrated terrain has advantage on all saving throws.
• Any celestial that enters desecrated terrain on its turn, or starts its turn there, takes 1d6 radiant damage.

An attack with holy water removes this effect from a 15-foot square of terrain centered on the point of attack.

If terrain becomes consecrated, it is no longer consecrated.

Any ground that is difficult to move through, such as thick mud or debris-covered floors, is difficult terrain. While moving through difficult terrain, you are Slowed.

There are three levels of illumination: bright light, dim light, and darkness.
  Bright light lets most creatures see normally. Even an overcast day or a torch is enough to provide some bright light.
  Dim light, or shadows, creates a lightly obscured area. An area of dim light is often a boundary between a source of bright light, and the darkness around. Soft light of twilight can also create dim light, as could a night under a luminous full moon.
  Darkness creates a heavily obscured area. Caves, dungeons, and unlit nights are often filled with darkness.

Fragile terrain includes crumbling floors or thin ice that can only support a creature’s weight only momentarily.

• If a creature uses any action on fragile terrain, or ends its turn there, the terrain crumbles away and the creature falls through, destroying a 5-foot square of the terrain directly underneath it. A creature can finish its action just before the floor gives away.
• A Large or larger creature instead falls through fragile terrain as soon as it enters the space, and destroys a proportionally larger square: 10 feet for Large, 15 feet for Huge, and 20 feet for Gargantuan.
• A Tiny creature instead doesn't fall through at all.
• Any damage to a 5-foot square of fragile terrain, except psychic damage, destroys the square. Fragile terrain has 5 defense.

Freezing water is found often in extreme cold, especially at sea.
  While you are submerged in freezing water, you are Soaked, and at the end of each of your turns you take 1 cold damage. While you remain Soaked in this water, any cold damage you take is maximized.
  Any creature with resistance or immunity to cold damage is unaffected, as does any creature acclimated to extreme cold.

Heavy precipitation often occurs alongside strong wind.

• Anything under heavy rain or snow is Soaked.
• Areas in heavy rain or snow are lightly obscured.
• Creatures in heavy precipitations have disadvantage on ability checks that rely on sight or hearing.

Most creatures need to breathe air. Aquatic creatures need to breathe water, and amphibious creatures need to breathe air or water. Undead, constructs, and some other creatures don't need to breathe.
  Holding Breath. You can hold your breath for a number of minutes equal to your Constitution modifier, but not less than 30 seconds (or 5 rounds).
  Out of Breath. If you must breathe and can no longer hold your breath, at the end of each of your turns you must succeed on a mark 20 Grit save or fall Unconscious and suffer Exhaustion. If already Unconscious this way, you must succeed on this save or suffer another degree of Exhaustion.

This hazard represents at least a 5‑foot patch of bush or ground that is currently aflame.
 When a creature first enters ignited terrain or starts its turn there, it must succeed on a mark 10 Reflex save or take 1d6 fire damage. A creature with resistance or immunity to fire damage needn't make this save.

Despite the flowing appearance lava sometimes has, it is literally molten rock. Due to its density, lava behaves more like an incredibly thick mud than a watery fluid.

• An area of lava is difficult terrain.
• When a creature first enters lava or starts its turn in there, it takes 10d6 fire damage and is Ignited.

A space might be lightly or heavily obscured.
  A lightly obscured area can result from dim light, patchy fog, or moderate foliage, for example. In a lightly obscured area, creatures have disadvantage on ability checks that rely on sight.
  A heavily obscured area can result from darkness, opaque smoke, or dense foliage, for example. Vision is completely blocked in a heavily obscured area, so creatures are effectively Blinded to anything within the area. Normally you can only Hide in a heavily obscured area, or while you have three-quarters cover.

Some effects may cause a creature, object, or other phenomenon to move, attack, or affect a random direction. To choose a random direction, you can roll a d8 on the following chart.

A result of 1 is north. Each increment above 1 is one more step clockwise through the eight cardinal directions.

While moving through slippery terrain, you are Slowed. Also, each time you enter an area of slippery terrain or start your turn there, you must succeed on a mark 10 Reflex save or fall Prone.
  A slippery slope — slippery terrain on a slope — cannot be ascended without specialized items or features, and you're not Slowed while descending it.
  Slippery ice is a special kind of slippery terrain that some creatures treat differently.

A slope is any particularly steep incline, with one direction ascending and the opposite direction descending.
  Any creature ascending the slope is Slowed while doing so, unless it isn't Slowed by climbing.
  A creature descending the slope is Fast while doing so, if either (a) the slope is slippery terrain or (b) the creature moves by rolling, such as on wheels.
  On a slope if a creature falls Prone, or a rolling object is not arrested, it Falls down the slope until it recovers from being Prone — or until its Fall is otherwise arrested.

Smoke — including particularly thick fog — can fill areas segmented into 5-foot cubes.

• Any area filled with smoke is heavily obscured, blocking vision in or through it.
• Any ranged attack made into or through smoke is made with disadvantage.
• You cannot breathe in smoke, and must hold your breath.
• If smoke overlaps with strong wind, that area of smoke is dispersed. If only part of a smoke cloud overlaps, only that part of the cloud is dispersed.

• All creatures in strong wind have disadvantage on ranged attack rolls and ability checks that rely on hearing.
• Flying is virtually impossible. If a creature ends its turn airborne in strong wind, it Falls.
• Everything within strong wind is immune to the Ignited condition.

Thorns are caused by natural plants, barbed wire, caltrops, or other effects. In game terms, thorns occupy 5-foot squares.

• You're Slowed while moving through thorns.
• When a creature first enters thorns or starts its turn in there, it must succeed on a mark 10 Reflex save or take 1d6 pierce damage.

• A protag with no leg attire has disadvantage on this save.

• Thorns can be destroyed. Each 5-foot square of thorns has a defense and max number of hit points equal to its save mark. Plant-based thorns take max fire and slash damage.

• Any creature that enters deep water becomes Soaked.
• While in water, a creature must swim to move. Unless a creature has a swim speed, it is Slowed while swimming.
• If not near the water's surface, you may need to hold your breath if you can't breathe water.

Underwater Attacks

• Attack rolls made underwater have disadvantage unless the weapon deals pierce damage, or the attack is made by an aquatic creature.
• A ranged attack roll made underwater can't hit beyond 20 feet, unless otherwise noted.

• Any creature that enters becomes Soaked.
• Such water is difficult terrain for creatures of Large size or smaller.
• Any Medium or Small creature can choose to swim in the water instead of walking, and use its swim speed if it has one.
• Any Tiny creature in such water has no choice but to swim.

These huge webs fill the territory of giant spiders or some predatory plants, and may persist even after these monsters have moved on.

• A creature moving through webs is Slowed.
• When a creature enters an area with webs or starts its turn there, it must succeed on a mark 10 Scuffle save or become Grappled by the webs. Attack rolls targeting a webbed creature have advantage.
• Webs can be destroyed, but they’re much tougher than the webbing of harmless Tiny spiders. Each 5-foot square of webs has defense and a max number of hit points equal to its save mark; it takes max slash and fire damage.