Natural Dangers
In the wide world, the scope of natural dangers, catastrophes, and challenges is wide indeed. Some are merely inconvenient or complicate an existing danger. Others go far beyond any mere environmental hazard, leaving death and devastation in their wake. A true catastrophe is much more like an adventure than an encounter, and does not have a specific Challenge Rating. Rather, each portion of the disaster should be treated as a separate encounter designed with a CR appropriate to the PCs.
Some disasters happen quickly, like earthquakes and tsunamis, while others progress through several stages, like forest fires, volcanoes, and undead uprisings. Game masters, adjust the pacing of the adventure to fit the disaster, allowing the events to unfold over mere minutes or over several days as your needs require.
On this page: Weather | Cold | Darkness | Falling | Heat | Volcanoes | Tsunamis
Weather
Weather can play an important role in an adventure.
| d% | Weather | Cold Climate | Temperate Climate1 | Desert |
|---|---|---|---|---|
| 01–70 | Normal weather | Cold, calm | Normal for season2 | Hot, calm |
| 71–80 | Abnormal weather | Heat wave (01–30) or cold snap (31–100) | Heat wave (01–50) or cold snap (51–100) | Hot, windy |
| 81–90 | Inclement weather | Precipitation (snow) | Precipitation (normal for season) | Hot, windy |
| 91–99 | Storm | Snowstorm | Thunderstorm, snowstorm | Duststorm |
| 100 | Powerful storm | Blizzard | Windstorm, blizzard, hurricane, tornado | Downpour |
| 1 Temperate includes forests, hills, marshes, mountains, plains, and warm aquatic environments. | ||||
| 2 Winter is cold, summer is warm, spring and autumn are temperate. Marsh regions are slightly warmer in winter. | ||||
Table: Random Weather can be used as a simple local weather table. Terms on that table are defined as follows.
Calm: Wind speeds are light (0 to 10 mph).
Cold: Between 0° and 40° Fahrenheit during the day, 10 to 20 degrees colder at night.
Cold Snap: Lowers temperature by -10° F.
Downpour: Treat as rain (see Precipitation, below), but conceals as fog. Can create floods. A downpour lasts for 2d4 hours.
Heat Wave: Raises temperature by +10° F.
Hot: Between 85° and 110° Fahrenheit during the day, 10 to 20 degrees colder at night.
Moderate: Between 40° and 60° Fahrenheit during the day, 10 to 20 degrees colder at night.
Powerful Storm (Windstorm/Blizzard/Hurricane/Tornado): Wind speeds are over 50 mph (see Table: Wind Effects). In addition, blizzards are accompanied by heavy snow (1d3 feet), and hurricanes are accompanied by downpours. Windstorms last for 1d6 hours. Blizzards last for 1d3 days. Hurricanes can last for up to a week, but their major impact on characters comes in a 24-to-48-hour period when the center of the storm moves through their area. Tornadoes are very short-lived (1d6 × 10 minutes), typically forming as part of a thunderstorm system.
Precipitation: Roll d% to determine whether the precipitation is fog (01–30), rain/snow (31–90), or sleet/hail (91–00). Snow and sleet occur only when the temperature is 30° Fahrenheit or below. Most precipitation lasts for 2d4 hours. By contrast, hail lasts for only 1d20 minutes but usually accompanies 1d4 hours of rain.
Storm (Duststorm/Snowstorm/Thunderstorm): Wind speeds are severe (30 to 50 mph) and visibility is cut by three-quarters. Storms last for 2d4-1 hours. See Storms, below, for more details.
Warm: Between 60° and 85° Fahrenheit during the day, 10 to 20 degrees colder at night.
Windy: Wind speeds are moderate to strong (10 to 30 mph); see Table: Wind Effects.
Rain, Snow, Sleet, and Hail
Bad weather frequently slows or halts travel and makes it virtually impossible to navigate from one spot to another. Torrential downpours and blizzards obscure vision as effectively as a dense fog.
Most precipitation is rain, but in cold conditions it can manifest as snow, sleet, or hail. Precipitation of any kind followed by a cold snap in which the temperature dips from above freezing to 30° F or below might produce ice.
Rain: Rain reduces visibility ranges by half, resulting in a -4 penalty on Perception checks. It has the same effect on flames, ranged weapon attacks, and Perception checks as severe wind.
Snow: Falling snow has the same effects on visibility, ranged weapon attacks, and skill checks as rain, and it costs 2 squares of movement to enter a snow-covered square. A day of snowfall leaves 1d6 inches of snow on the ground.
Heavy Snow: Heavy snow has the same effects as normal snowfall but also restricts visibility as fog does (see Fog). A day of heavy snow leaves 1d4 feet of snow on the ground, and it costs 4 squares of movement to enter a square covered with heavy snow. Heavy snow accompanied by strong or severe winds might result in snowdrifts 1d4 × 5 feet deep, especially in and around objects big enough to deflect the wind — a cabin or a large tent, for instance. There is a 10% chance that a heavy snowfall is accompanied by lightning (see Thunderstorm). Snow has the same effect on flames as moderate wind.
Sleet: Essentially frozen rain, sleet has the same effect as rain while falling (except that its chance to extinguish protected flames is 75%) and the same effect as snow once on the ground.
Hail: Hail does not reduce visibility, but the sound of falling hail makes sound-based Perception checks more difficult (-4 penalty). Sometimes (5% chance) hail can become large enough to deal 1 point of lethal damage (per storm) to anything in the open. Once on the ground, hail has the same effect on movement as snow.
Storms
The combined effects of precipitation (or dust) and wind that accompany all storms reduce visibility ranges by three-quarters, imposing a -8 penalty on Perception checks. Storms make ranged weapon attacks impossible, except for those using siege weapons, which have a -4 penalty on attack rolls. They automatically extinguish candles, torches, and similar unprotected flames. They cause protected flames, such as those of lanterns, to dance wildly and have a 50% chance to extinguish these lights. See Table: Wind Effects for possible consequences to creatures caught outside without shelter during such a storm. Storms are divided into the following three types.
Duststorm (CR 3): These desert storms differ from other storms in that they have no precipitation. Instead, a duststorm blows fine grains of sand that obscure vision, smother unprotected flames, and can even choke protected flames (50% chance). Most duststorms are accompanied by severe winds and leave behind a deposit of 1d6 inches of sand. There is a 10% chance for a greater duststorm to be accompanied by windstorm-magnitude winds (see Table: Wind Effects). These greater duststorms deal 1d3 points of nonlethal damage each round to anyone caught out in the open without shelter and also pose a choking hazard (see Drowning, except that a character with a scarf or similar protection across her mouth and nose does not begin to choke until after a number of rounds equal to 10 + her Constitution score). Greater duststorms leave 2d3-1 feet of fine sand in their wake.
Snowstorm: In addition to the wind and precipitation common to other storms, snowstorms leave 1d6 inches of snow on the ground afterward.
Thunderstorm: In addition to wind and precipitation (usually rain, but sometimes also hail), thunderstorms are accompanied by lightning that can pose a hazard to characters without proper shelter (especially those in metal armor). As a rule of thumb, assume one bolt per minute for a 1-hour period at the center of the storm. Each bolt causes between 4d8 and 10d8 points of electricity damage. One in 10 thunderstorms is accompanied by a tornado.
Powerful Storms: Very high winds and torrential precipitation reduce visibility to zero, making Perception checks and all ranged weapon attacks impossible. Unprotected flames are automatically extinguished, and protected flames have a 75% chance of being doused. Creatures caught in the area must make a Fortitude save or face the effects based on the size of the creature (see Table: Wind Effects). Powerful storms are divided into the following four types.
Windstorm: While accompanied by little or no precipitation, windstorms can cause considerable damage simply through the force of their winds.
Blizzard: The combination of high winds, heavy snow (typically 1d3 feet), and bitter cold make blizzards deadly for all who are unprepared for them.
Hurricane: In addition to very high winds and heavy rain, hurricanes are accompanied by floods. Most adventuring activity is impossible under such conditions.
Tornado: In addition to incredibly high winds, tornadoes can severely injure and kill those that get pulled into their funnels.
Fog
Whether in the form of a low-lying cloud or a mist rising from the ground, fog obscures all sight beyond 5 feet, including darkvision. Creatures 5 feet away have concealment (attacks by or against them have a 20% miss chance).
Winds
The wind can create a stinging spray of sand or dust, fan a large fire, keel over a small boat, and blow gases or vapors away. If powerful enough, it can even knock characters down (see Table: Wind Effects), interfere with ranged attacks, or impose penalties on some skill checks.
| Wind Force | Wind Speed | Ranged Attacks Normal/Siege Weapons1 | Checked Size2 | Blown Away Size | Fly Penalty |
|---|---|---|---|---|---|
| Light | 0–10 mph | — / — | — | — | — |
| Moderate | 11–20 mph | — / — | — | — | — |
| Strong | 21–30 mph | -2/ — | Tiny | — | -2 |
| Severe | 31–50 mph | -4/ — | Small | Tiny | -4 |
| Windstorm | 51–74 mph | Impossible/-4 | Medium | Small | -8 |
| Hurricane | 75–174 mph | Impossible/-8 | Large | Medium | -12 |
| Tornado | 175–300 mph | Impossible/impossible | Huge | Large | -16 |
| 1 The siege weapon category includes ballista and catapult attacks as well as boulders tossed by giants. | |||||
| 2 Checked Size: Creatures of this size or smaller are unable to move forward against the force of the wind unless they succeed on a DC 10 Strength check (if on the ground) or a DC 20 Fly skill check if airborne. | |||||
| 3 Blown Away Size: Creatures on the ground are knocked prone and rolled 1d4 × 10 feet, taking 1d4 points of nonlethal damage per 10 feet, unless they make a DC 15 Strength check. Flying creatures are blown back 2d6 × 10 feet and take 2d6 points of nonlethal damage due to battering and buffeting, unless they succeed on a DC 25 Fly skill check. | |||||
Light Wind: A gentle breeze, having little or no game effect.
Moderate Wind: A steady wind with a 50% chance of extinguishing small, unprotected flames, such as candles.
Strong Wind: Gusts that automatically extinguish unprotected flames (candles, torches, and the like). Such gusts impose a -2 penalty on ranged attack rolls and on Perception checks.
Severe Wind: In addition to automatically extinguishing any unprotected flames, winds of this magnitude cause protected flames (such as those of lanterns) to dance wildly and have a 50% chance of extinguishing these lights. Ranged weapon attacks and Perception checks are at a -4 penalty. This is the velocity of wind produced by a gust of wind spell.
Windstorm: Powerful enough to bring down branches if not whole trees, windstorms automatically extinguish unprotected flames and have a 75% chance of blowing out protected flames, such as those of lanterns. Ranged weapon attacks are impossible, and even siege weapons have a -4 penalty on attack rolls. Perception checks that rely on sound are at a -8 penalty due to the howling of the wind.
Hurricane-Force Wind: All flames are extinguished. Ranged attacks are impossible (except with siege weapons, which have a -8 penalty on attack rolls). Perception checks based on sound are impossible: all characters can hear is the roaring of the wind. Hurricane-force winds often fell trees.
Tornado (CR 10): All flames are extinguished. All ranged attacks are impossible (even with siege weapons), as are sound-based Perception checks. Instead of being blown away (see Table: Wind Effects), characters in close proximity to a tornado who fail their Fortitude saves are sucked toward the tornado. Those who come in contact with the actual funnel cloud are picked up and whirled around for 1d10 rounds, taking 6d6 points of damage per round, before being violently expelled (falling damage might apply). While a tornado's rotational speed can be as great as 300 mph, the funnel itself moves forward at an average of 30 mph (roughly 250 feet per round). A tornado uproots trees, destroys buildings, and causes similar forms of major destruction.
Cold Dangers
Cold and exposure deal nonlethal damage to the victim. A character cannot recover from the damage dealt by a cold environment until she gets out of the cold and warms up again. Once a character has taken an amount of nonlethal damage equal to her total hit points, any further damage from a cold environment is lethal damage.
An unprotected character in cold weather (below 40° F)must make a Fortitude save each hour (DC 15, +1 per previous check) or take 1d6 points of nonlethal damage. A character who has the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well (see the skill description).
In conditions of severe cold or exposure (below 0° F), an unprotected character must make a Fortitude save once every 10 minutes (DC 15, +1 per previous check), taking 1d6 points of nonlethal damage on each failed save. A character who has the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well. Characters wearing a cold weather outfit only need check once per hour for cold and exposure damage.
A character who takes any nonlethal damage from cold or exposure is beset by frostbite or hypothermia (treat her as fatigued). These penalties end when the character recovers the nonlethal damage she took from the cold and exposure.
Extreme cold (below -20° F) deals 1d6 points of lethal damage per minute (no save). In addition, a character must make a Fortitude save (DC 15, +1 per previous check) or take 1d4 points of nonlethal damage.
Ice Effects
Characters walking on ice must spend 2 squares of movement to enter a square covered by ice, and the DC for Acrobatics checks increases by +5. Characters in prolonged contact with ice might run the risk of taking damage from severe cold.
Darkness
Darkvision allows many characters and monsters to see perfectly well without any light at all, but characters with normal or low-light vision can be rendered completely blind by putting out the lights. Torches or lanterns can be blown out by sudden gusts of subterranean wind, magical light sources can be dispelled or countered, or magical traps might create fields of impenetrable darkness.
In many cases, some characters or monsters might be able to see while others are blinded. For purposes of the following points, a blinded creature is one who simply can't see through the surrounding darkness.
Creatures blinded by darkness lose the ability to deal extra damage due to precision (for example, via sneak attack or a duelist's precise strike ability).
Blind creatures must make a DC 10 Acrobatics skill check to move faster than half speed. Creatures that fail this check fall prone. Blinded creatures can't run or charge.
All opponents have total concealment from a blinded creature, so the blinded creature has a 50% miss chance in combat. A blinded creature must first pinpoint the location of an opponent in order to attack the right square; if the blinded creature launches an attack without pinpointing its foe, it attacks a random square within its reach. For ranged attacks or spells against a foe whose location is not pinpointed, roll to determine which adjacent square the blinded creature is facing; its attack is directed at the closest target that lies in that direction.
A blinded creature loses its Dexterity modifier to AC (if positive) and takes a -2 penalty to AC.
A blinded creature takes a -4 penalty on Perception checks and most Strength- and Dexterity-based skill checks, including any with an armor check penalty. A creature blinded by darkness automatically fails any skill check relying on vision.
Creatures blinded by darkness cannot use gaze attacks and are immune to gaze attacks.
A creature blinded by darkness can make a Perception check as a free action each round in order to locate foes (DC equal to opponents' Stealth checks). A successful check lets a blinded character hear an unseen creature “over there somewhere.” It's almost impossible to pinpoint the location of an unseen creature. A Perception check that beats the DC by 20 reveals the unseen creature's square (but the unseen creature still has total concealment from the blinded creature).
A blinded creature can grope about to find unseen creatures. A character can make a touch attack with his hands or a weapon into two adjacent squares using a standard action. If an unseen target is in the designated square, there is a 50% miss chance on the touch attack. If successful, the groping character deals no damage but has pinpointed the unseen creature's current location. If the unseen creature moves, its location is once again unknown.
If a blinded creature is struck by an unseen foe, the blinded character pinpoints the location of the creature that struck him (until the unseen creature moves, of course). The only exception is if the unseen creature has a reach greater than 5 feet (in which case the blinded character knows the location of the unseen opponent, but has not pinpointed him) or uses a ranged attack (in which case the blinded character knows the general direction of the foe, but not his location).
A creature with the scent ability automatically pinpoints unseen creatures within 5 feet of its location.
Falling
Creatures that fall take 1d6 points of damage per 10 feet fallen, to a maximum of 20d6. Creatures that take lethal damage from a fall land in a prone position.
If a character deliberately jumps instead of merely slipping or falling, the damage is the same but the first 1d6 is nonlethal damage. A DC 15 Acrobatics check allows the character to avoid any damage from the first 10 feet fallen and converts any damage from the second 10 feet to nonlethal damage. Thus, a character who slips from a ledge 30 feet up takes 3d6 damage. If the same character deliberately jumps, he takes 1d6 points of nonlethal damage and 2d6 points of lethal damage. And if the character leaps down with a successful Acrobatics check, he takes only 1d6 points of nonlethal damage and 1d6 points of lethal damage from the plunge.
Falls onto yielding surfaces (soft ground, mud) also convert the first 1d6 of damage to nonlethal damage. This reduction is cumulative with reduced damage due to deliberate jumps and the Acrobatics skill.
A character cannot cast a spell while falling, unless the fall is greater than 500 feet or the spell is an immediate action, such as feather fall. Casting a spell while falling requires a concentration check with a DC equal to 20 + the spell's level. Casting teleport or a similar spell while falling does not end your momentum, it just changes your location, meaning that you still take falling damage, even if you arrive atop a solid surface.
Falling into Water: Falls into water are handled somewhat differently. If the water is at least 10 feet deep, the first 20 feet of falling do no damage. The next 20 feet do nonlethal damage (1d3 per 10-foot increment). Beyond that, falling damage is lethal damage (1d6 per additional 10-foot increment).
Characters who deliberately dive into water take no damage on a successful DC 15 Swim check or DC 15 Acrobatics check, so long as the water is at least 10 feet deep for every 30 feet fallen. The DC of the check, however, increases by 5 for every 50 feet of the dive.
Falling Objects
| Object Size | Damage |
|---|---|
| Small | 2d6 |
| Medium | 3d6 |
| Large | 4d6 |
| Huge | 6d6 |
| Gargantuan | 8d6 |
| Colossal | 10d6 |
Just as characters take damage when they fall more than 10 feet, so too do they take damage when they are hit by falling objects.
Objects that fall upon characters deal damage based on their size and the distance they have fallen. Table: Damage from Falling Objects determines the amount of damage dealt by an object based on its size. Note that this assumes that the object is made of dense, heavy material, such as stone. Objects made of lighter materials might deal as little as half the listed damage, subject to GM discretion. For example, a Huge boulder that hits a character deals 6d6 points of damage, whereas a Huge wooden wagon might deal only 3d6 damage. In addition, if an object falls less than 30 feet, it deals half the listed damage. If an object falls more than 150 feet, it deals double the listed damage. Note that a falling object takes the same amount of damage as it deals.
Dropping an object on a creature requires a ranged touch attack. Such attacks generally have a range increment of 20 feet. If an object falls on a creature (instead of being thrown), that creature can make a DC 15 save to halve the damage if he is aware of the object. Falling objects that are part of a trap use the trap rules instead of these general guidelines.
Heat Dangers
Heat deals nonlethal damage that cannot be recovered from until the character gets cooled off (reaches shade, survives until nightfall, gets doused in water, is targeted by endure elements, and so forth). Once a character has taken an amount of nonlethal damage equal to her total hit points, any further damage from a hot environment is lethal damage.
A character in very hot conditions (above 90° F) must make a Fortitude saving throw each hour (DC 15, +1 for each previous check) or take 1d4 points of nonlethal damage. Characters wearing heavy clothing or armor of any sort take a -4 penalty on their saves. A character with the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well (see the skill description). Characters reduced to unconsciousness begin taking lethal damage (1d4 points per hour).
In severe heat (above 110° F), a character must make a Fortitude save once every 10 minutes (DC 15, +1 for each previous check) or take 1d4 points of nonlethal damage. Characters wearing heavy clothing or armor of any sort take a -4 penalty on their saves. A character with the Survival skill may receive a bonus on this saving throw and might be able to apply this bonus to other characters as well (see the Survival skill). Characters reduced to unconsciousness begin taking lethal damage (1d4 points per each 10-minute period).
A character who takes any nonlethal damage from heat exposure now suffers from heatstroke and is fatigued. These penalties end when the character recovers from the nonlethal damage she took from the heat.
Extreme heat (air temperature over 140° F, fire, boiling water, lava) deals lethal damage. Breathing air in these temperatures deals 1d6 points of fire damage per minute (no save). In addition, a character must make a Fortitude save every 5 minutes (DC 15, +1 per previous check) or take 1d4 points of nonlethal damage. Those wearing heavy clothing or any sort of armor take a -4 penalty on their saves.
Boiling water deals 1d6 points of scalding damage, unless the character is fully immersed, in which case it deals 10d6 points of damage per round of exposure.
Smoke Effects
A character who breathes heavy smoke must make a Fortitude save each round (DC 15, +1 per previous check) or spend that round choking and coughing. A character who chokes for 2 consecutive rounds takes 1d6 points of nonlethal damage. Smoke obscures vision, giving concealment (20% miss chance) to characters within it.
Catching on Fire
Characters exposed to burning oil, bonfires, and non-instantaneous magic fires might find their clothes, hair, or equipment on fire. Spells with an instantaneous duration don't normally set a character on fire, since the heat and flame from these come and go in a flash.
Characters at risk of catching fire are allowed a DC 15 save to avoid this fate. If a character's clothes or hair catch fire, he takes 1d6 points of damage immediately. In each subsequent round, the burning character must make another saving throw. Failure means he takes another 1d6 points of damage that round. Success means that the fire has gone out — that is, once he succeeds on his saving throw, he's no longer on fire.
A character on fire may automatically extinguish the flames by jumping into enough water to douse himself. If no body of water is at hand, rolling on the ground or smothering the fire with cloaks or the like permits the character another save with a +4 bonus.
Those whose clothes or equipment catch fire must make DC 15 saves for each item. Flammable items that fail take the same amount of damage as the character.
Lava Effects
Lava or magma deals 2d6 points of damage per round of exposure, except in the case of total immersion (such as when a character falls into the crater of an active volcano), which deals 20d6 points of damage per round.
Damage from lava continues for 1d3 rounds after exposure ceases, but this additional damage is only half of that dealt during actual contact (that is, 1d6 or 10d6 points per round). Immunity or resistance to fire serves as an immunity to lava or magma. A creature immune to fire might still drown if completely immersed in lava (see Drowning).
Starvation and Thirst
Characters might find themselves without food or water and with no means to obtain them. In normal climates, Medium characters need at least a gallon of fluids and about a pound of decent food per day to avoid starvation. (Small characters need half as much.) In very hot climates, characters need two or three times as much water to avoid dehydration.
A character can go without water for 1 day plus a number of hours equal to his Constitution score. After this time, the character must make a Constitution check each hour (DC 10, +1 for each previous check) or take 1d6 points of nonlethal damage. Characters that take an amount of nonlethal damage equal to their total hit points begin to take lethal damage instead.
A character can go without food for 3 days, in growing discomfort. After this time, the character must make a Constitution check each day (DC 10, +1 for each previous check) or take 1d6 points of nonlethal damage. Characters that take an amount of nonlethal damage equal to their total hit points begin to take lethal damage instead.
Characters who have taken nonlethal damage from lack of food or water are fatigued. Nonlethal damage from thirst or starvation cannot be recovered until the character gets food or water, as needed — not even magic that restores hit points heals this damage.
Suffocation
A character who has no air to breathe can hold her breath for 2 rounds per point of Constitution. If a character takes a standard or full-round action, the remaining duration that the character can hold her breath is reduced by 1 round. After this period of time, the character must make a DC 10 Constitution check in order to continue holding her breath. The check must be repeated each round, with the DC increasing by +1 for each previous success.
When the character fails one of these Constitution checks, she begins to suffocate. In the first round, she falls unconscious (0 hit points). In the following round, she drops to -1 hit points and is dying. In the third round, she suffocates.
Slow Suffocation: A Medium character can breathe easily for 6 hours in a sealed chamber measuring 10 feet on a side. After that time, the character takes 1d6 points of nonlethal damage every 15 minutes. Each additional Medium character or significant fire source (a torch, for example) proportionally reduces the time the air will last. Once rendered unconscious through the accumulation of nonlethal damage, the character begins to take lethal damage at the same rate. Small characters consume half as much air as Medium characters.
Water Dangers
Any character can wade in relatively calm water that isn't over his head, no check required. Similarly, swimming in calm water only requires Swim skill checks with a DC of 10. Trained swimmers can just take 10. Remember, however, that armor or heavy gear makes any attempt at swimming much more difficult (see the Swim skill description).
By contrast, fast-moving water is much more dangerous. Characters must make a successful DC 15 Swim check or a DC 15 Strength check to avoid going under. On a failed check, the character takes 1d3 points of nonlethal damage per round (1d6 points of lethal damage if flowing over rocks and cascades).
Very deep water is not only generally pitch black, posing a navigational hazard, but worse, deals water pressure damage of 1d6 points per minute for every 100 feet the character is below the surface. A successful Fortitude save (DC 15, +1 for each previous check) means the diver takes no damage in that minute. Very cold water deals 1d6 points of nonlethal damage from hypothermia per minute of exposure.
Drowning
Any character can hold her breath for a number of rounds equal to twice her Constitution score. If a character takes a standard or full-round action, the remaining duration that the character can hold her breath is reduced by 1 round. After this period of time, the character must make a DC 10 Constitution check every round in order to continue holding her breath. Each round, the DC increases by 1.
When the character finally fails her Constitution check, she begins to drown. In the first round, she falls unconscious (0 hp). In the following round, she drops to -1 hit points and is dying. In the third round, she drowns.
>Unconscious characters must begin making Constitution checks immediately upon being submerged (or upon becoming unconscious if the character was conscious when submerged). Once she fails one of these checks, she immediately drops to -1 (or loses 1 additional hit point, if her total is below -1). On the following round, she drowns.
It is possible to drown in substances other than water, such as sand, quicksand, fine dust, and silos full of grain.
Volcanoes
When the world's crust ruptures and expels its molten heart, one of the most dramatic natural disasters results: a volcano. Volcanic eruptions offer a wide range of options for the GM, including lava, lava bombs, poisonous gases, and pyroclastic flows. GMs might also consider presaging a dramatic volcanic eruption with existing hazards, like avalanches and minor earthquakes.
Lava
Lava flows are usually associated with nonexplosive eruptions, and can be a permanent fixture of active volcanoes. Most lava flows are quite slow, moving at 15 feet per round. Hotter flows move faster, achieving speeds up to 60 feet per round. Lava in a channel such as a lava tube is especially dangerous, moving as fast as 120 feet per round (a CR 6 hazard). Creatures overrun by a lava flow must make a DC 20 Reflex save or be engulfed in the lava. Success indicates that they are in contact with the lava but not immersed.
Lava Bombs (CR 2 or 8)
Blobs of molten rock may be hurled several miles from an erupting volcano, cooling into solid rock before they land. A typical lava bomb strikes a point designated by the GM and explodes in a 30-foot radius. All creatures in the area must make a DC 15 Reflex save or take 4d6 points of damage. Creatures under cover or capable of covering themselves (like with a shield) gain a +2 bonus on this save. Particularly large lava bombs might sometimes occur, dealing 12d6 points of damage. Normal lava bombs have a CR of 2, large lava bombs have a CR of 5.
Poisonous Gas (CR 5)
One of the more insidious threats of a volcano is toxic gas, often escaping notice amid the fire and destruction. A wide variety of poisonous vapors can result from a volcanic eruption, some visible, some unseen. Poisonous gas causes 1d6 points of Constitution damage per round if inhaled (Fortitude DC 15 negates, the DC increases by 1 per previous save), and visible gases also function as heavy smoke. Poisonous gas clouds flow toward low ground, and are typically 50 feet high. Gale-force winds can divert gas clouds, as can high barriers — provided the gas has somewhere else to go.
Pyroclastic Flows (CR 10)
Some volcanic eruptions create a devastating wave of burning ash, hot gases, and volcanic debris called a pyroclastic flow that can travel for miles. Treat a pyroclastic flow as an avalanche traveling at 500 feet per round, combined with the effects of poisonous gas listed above. Contact with the searing-hot debris of the flow causes 2d6 points of fire damage per round, while any creature buried in the flow suffers 10d6 points of damage per round. Only reality-warping magic like miracle or wish can turn aside or impede a pyroclastic flow.
Tsunamis
Tsunamis, sometimes referred to as tidal waves, are crushing waves of water caused by underwater earthquakes, volcanic explosions, landslides, or even asteroid impacts. Tsunamis are almost undetectable until they reach shallow water, at which point the mass of water builds up into a great wave.
Depending on the size of the tsunami and the slope of the shore, the wave can travel anywhere from hundreds of yards to more than a mile inland, leaving destruction in its wake. The water then drains back, dragging all manner of debris and creatures far out to sea.
The exact damage caused by a tsunami is subject to the GM's discretion, but a typical tsunami obliterates or displaces all temporary and poorly built structures in its path, destroys about 25% of well-built buildings (and causes significant damage to those that survive), and leaves serious fortifications only lightly damaged. As much as a quarter of the population living in the area (including animals and monsters) perishes in the disaster, either swept out to sea, drowned on shore, or buried under rubble.
A creature can avoid being pulled out to sea with a DC 25 Swim check; otherwise it is pulled 6d6 × 10 feet away from shore. Waters after a tsunami are always treated as rough or stormy, barring magical influence. A creature caught in a collapsing building takes 6d6 points of damage (DC 15 Reflex save for half), or half that amount if the building is particularly small. There is a 50% chance that the creature is buried (as for a cave-in), or the tsunami may tear the building apart, freeing the creature from the rubble.