Flagstone: Like masonry walls, flagstone floors are made of fitted stones. They are usually cracked and only somewhat level. Slime and mold grows in these cracks. Sometimes water runs in rivulets between the stones or sits in stagnant puddles. Flagstone is the most common dungeon floor.

Uneven Flagstone: Over time, some floors can become so uneven that a DC 10 Balance check is required to run or charge across the surface. Failure means the character can’t move in this round. Floors as treacherous as this should be the exception, not the rule.

Hewn Stone Floors: Rough and uneven, hewn floors are usually covered with loose stones, gravel, dirt, or other debris. A DC 10 Balance check is required to run or charge across such a floor. Failure means the character can still act, but can’t run or charge in this round.

Light Rubble: Small chunks of debris litter the ground. Light rubble adds 2 to the DC of Balance and Tumble checks.

Dense Rubble: The ground is covered with debris of all sizes. It costs 2 squares of movement to enter a square with dense rubble. Dense rubble adds 5 to the DC of Balance and Tumble checks, and it adds 2 to the DC of Move Silently checks.

Smooth Stone Floors: Finished and sometimes even polished, smooth floors are found only in dungeons with capable and careful builders.

Natural Stone Floors: The floor of a natural cave is as uneven as the walls. Caves rarely have flat surfaces of any great size. Rather, their floors have many levels. Some adjacent floor surfaces might vary in elevation by only a foot, so that moving from one to the other is no more difficult than negotiating a stair step, but in other places the floor might suddenly drop off or rise up several feet or more, requiring Climb checks to get from one surface to the other. Unless a path has been worn and well marked in the floor of a natural cave, it takes 2 squares of movement to enter a square with a natural stone floor, and the DC of Balance and Tumble checks increases by 5. Running and charging are impossible, except along paths.

Slippery: Water, ice, slime, or blood can make any of the dungeon floors described in this section more treacherous. Slippery floors increase the DC of Balance and Tumblechecks by 5.

Grate: A grate often covers a pit or an area lower than the main floor. Grates are usually made from iron, but large ones can also be made from iron-bound timbers. Many grates have hinges to allow access to what lies below (such grates can be locked like any door), while others are permanent and designed not to move. A typical 1-inch-thick iron grate has 25 hit points, hardness 10, and a DC of 27 for Strength checks to break through it or tear it loose.

Ledge: Ledges allow creatures to walk above some lower area. They often circle around pits, run along underground streams, form balconies around large rooms, or provide a place for archers to stand while firing upon enemies below. Narrow ledges (12 inches wide or less) require those moving along them to make Balance checks. Failure results in the moving character falling off the ledge. Ledges sometimes have railings. In such a case, characters gain a +5 circumstance bonus on Balance checks to move along the ledge. A character who is next to a railing gains a +2 circumstance bonus on his or her opposed Strength check to avoid being bull rushed off the edge.

Ledges can also have low walls 2 to 3 feet high along their edges. Such walls provide cover against attackers within 30 feet on the other side of the wall, as long as the target is closer to the low wall than the attacker is.

Transparent Floor: Transparent floors, made of reinforced glass or magic materials (even a wall of force), allow a dangerous setting to be viewed safely from above. Transparent floors are sometimes placed over lava pools, arenas, monster dens, and torture chambers. They can be used by defenders to watch key areas for intruders.

Sliding Floors: A sliding floor is a type of trapdoor, designed to be moved and thus reveal something that lies beneath it. A typical sliding floor moves so slowly that anyone standing on one can avoid falling into the gap it creates, assuming there’s somewhere else to go. If such a floor slides quickly enough that there’s a chance of a character falling into whatever lies beneath-a spiked pit, a vat of burning oil, or a pool filled with sharks-then it’s a trap.

Trap Floors: Some floors are designed to become suddenly dangerous. With the application of just the right amount of weight, or the pull of a lever somewhere nearby, spikes protrude from the floor, gouts of steam or flame shoot up from hidden holes, or the entire floor tilts. These strange floors are sometimes found in an arena, designed to make combats more exciting and deadly. Construct these floors as you would any other trap.

Characters walking on ice must spend 2 squares of movement to enter a square covered by ice, and the DC for Balance and Tumble checks increases by +5. Characters in prolonged contact with ice may run the risk of taking damage from severe cold.

Stairs: The usual way to connect different levels of a dungeon is with stairs. Straight stairways, spiral staircases, or stairwells with multiple landings between flights of stairs are all common in dungeons, as are ramps (sometimes with an incline so slight that it can be difficult to notice; Spot DC 15). Stairs are important accessways, and are sometimes guarded or trapped. Traps on stairs often cause intruders to slide or fall down to the bottom, where a pit, spikes, a pool of acid, or some other danger awaits.

Gradual Stairs: Stairs that rise less than 5 feet for every 5 feet of horizontal distance they cover don’t affect movement, but characters who attack a foe below them gain a +1 bonus on attack rolls from being on higher ground. Most stairs in dungeons are gradual, except for spiral stairs (see below).

Steep Stairs: Characters moving up steep stairs (which rise at a 45- degree angle or steeper) must spend 2 squares of movement to enter each square of stairs. Characters running or charging down steep stairs must succeed on a DC 10 Balance check upon entering the first steep stairs square. Characters who fail stumble and must end their movement 1d2×5 feet later. Characters who fail by 5 or more take 1d6 points of damage and fall prone in the square where they end their movement. Steep stairs increase the DC of Tumble checks by 5.

Spiral Stairs: This form of steep stairs is designed to make defending a fortress easier. Characters gain cover against foes below them on spiral stairs because they can easily duck around the staircase’s central support.

Railings and Low Walls: Stairs that are open to large rooms often have railings or low walls. They function as described for ledges (see Special Floors).

Bridge: A bridge connects two higher areas separated by a lower area, stretching across a chasm, over a river, or above a pit. A simple bridge might be a single wooden plank, while an elaborate one could be made of mortared stone with iron supports and side rails.

Narrow Bridge: If a bridge is particularly narrow, such as a series of planks laid over lava fissures, treat it as a ledge (see Special Floors). It requires a Balance check (DC dependent on width) to cross such a bridge.

Rope Bridge: Constructed of wooden planks suspended from ropes, a rope bridge is convenient because it’s portable and can be easily removed. It takes two full-round actions to untie one end of a rope bridge, but a DC 15 Use Rope check reduces the time to a move action. If only one of the two supporting ropes is attached, everyone on the bridge must succeed on a DC 15 Reflex save to avoid falling off, and thereafter must make DC 15 Climb checks to move along the remnants of the bridge. Rope bridges are usually 5 feet wide. The two ropes that support them have 8 hit points each.

Drawbridge: Some bridges have mechanisms that allow them to be extended or retracted from the gap they cross. Typically,  the winch mechanism exists on only one side of the bridge. It takes a move action to lower a drawbridge, but the bridge doesn’t come down until the beginning of the lowering character’s next turn. It takes a full-round action to raise a drawbridge; the drawbridge is up at the end of the action. Particularly long or wide drawbridges may take more time to raise and lower, and some may require Strength checks to rotate the winch.

Railings and Low Walls: Some bridges have railings or low walls along the sides. If a bridge does, the railing or low walls affect Balance checks and bull rush attempts as described for ledges (see Special Floors). Low walls likewise provide cover to bridge occupants.

Chutes and Chimneys: Stairs aren’t the only way to move up and down in a dungeon. Sometimes a vertical shaft connects levels of a dungeon or links a dungeon with the surface. Chutes are usually traps that dump characters into a lower area-often a place featuring some dangerous situation with which they must contend.

Pillar: A common sight in any dungeon, pillars and columns give support to ceilings. The larger the room, the more likely it has pillars. As a rule of thumb, the deeper in the dungeon a room is, the thicker the pillars need to be to support the overhead weight. Pillars tend to be polished and often have carvings, paintings, or inscriptions upon them.

Slender Pillar: These pillars are only a foot or two across, so they don’t occupy a whole square. A creature standing in the same square as a slender pillar gains a +2 cover bonus to Armor Class and a +1 cover bonus on Reflex saves (these bonuses don’t stack with cover bonuses from other sources). The presence of a slender pillar does not otherwise affect a creature’s fighting space, because it’s assumed that the creature is using the pillar to its advantage when it can. A typical slender pillar has AC 4, hardness 8, and 250 hit points.

Wide Pillar: These pillars take up an entire square and provide cover to anyone behind them. They have AC 3, hardness 8, and 900 hit points. A DC 20 Climb check is sufficient to climb most pillars; the DC increases to 25 for polished or unusually slick ones.

Stalagmite/Stalactite: These tapering natural rock columns extend from the floor (stalagmite) or the ceiling (stalactite). Stalagmites and stalactites function as slender pillars.

Statue: Most statues function as wide pillars, taking up a square and providing cover. Some statues are smaller and act as slender pillars. A DC 15 Climb check allows a character to climb a statue.

Tapestry: Elaborately embroidered patterns or scenes on cloth, tapestries hang from the walls of well-appointed dungeon rooms or corridors. Crafty builders take advantage of tapestries to place alcoves, concealed doors, or secret switches behind them.

Tapestries provide total concealment (50% miss chance) to characters behind them if they’re hanging from the ceiling, or concealment (20% miss chance) if they’re flush with the wall. Climbing a big tapestry isn’t particularly difficult, requiring a DC 15 Climb check (or DC 10 if a wall is within reach).

Pedestal: Anything important on display in a dungeon, from a fabulous treasure to a coffin, tends to rest atop a pedestal or a dais. Raising the object off the floor focuses attention on it (and, in practical terms, keeps it safe from any water or other substance that might seep onto the floor). A pedestal is often trapped to protect whatever sits atop it. It can conceal a secret trapdoor beneath itself or provide a way to reach a door in the ceiling above itself.

Only the largest pedestals take up an entire square; most provide no cover.

Pool: Pools of water collect naturally in low spots in dungeons (a dry dungeon is rare). Pools can also be wells or natural underground springs, or they can be intentionally created basins, cisterns, and fountains. In any event, water is fairly common in dungeons, harboring sightless fish and sometimes aquatic monsters. Pools provide water for dungeon denizens, and thus are as important an area for a predator to control as a watering hole aboveground in the wild.

Shallow Pool: If a square contains a shallow pool, it has roughly 1 foot of standing water. It costs 2 squares of movement to move into a square with a shallow pool, and the DC of Tumble checks in such squares increases by 2.

Deep Pool: These squares have at least 4 feet of standing water. It costs Medium or larger creatures 4 squares of movement to move into a square with a deep pool, or characters can swim if they wish. Small or smaller creatures must swim to move through a square containing a deep pool. Tumbling is impossible in a deep pool. The water in a deep pool provides cover for Medium or larger creatures. Smaller creatures gain improved cover (+8 bonus to AC, +4 bonus on Reflex saves). Medium or larger creatures can crouch as a move action to gain this improved cover. Creatures with this improved cover take a -10 penalty on attacks against creatures that aren’t also underwater.

Deep pool squares are usually clustered together and surrounded by a ring of shallow pool squares. Both shallow pools and deep pools impose a -2 circumstance penalty on Move Silently checks.

Special Pools: Through accident or design, a pool can become magically enhanced. Rarely, a pool or a fountain may be found that has the ability to bestow beneficial magic on those who drink from it. However, magic pools are just as likely to curse the drinker. Typically, water from a magic pool loses its potency if removed from the pool for more than an hour or so.

Some pools have fountains. Occasionally these are merely decorative, but they often serve as the focus of a trap or the source of a pool’s magic.

Most pools are made of water, but anything’s possible in a dungeon. Pools can hold unsavory substances such as blood, poison, oil, or magma. And even if a pool holds water, it can be holy water, saltwater, or water tainted with disease.

Elevator: In place of or in addition to stairs, an elevator (essentially an oversized dumbwaiter) can take inhabitants from one dungeon level to the next. Such an elevator may be mechanical (using gears, pulleys, and winches) or magical (such as a levitate spell cast on a movable flat surface). A mechanical elevator might be as small as a platform that holds one character at a time, or as large as an entire room that raises and lowers. A clever builder might design an elevator room that moves up or down without the occupants’ knowledge to catch them in a trap, or one that appears to have moved when it actually remained still.

A typical elevator ascends or descends 10 feet per round at the beginning of the operator’s turn (or on initiative count 0 if it functions without regard to whether creatures are on it. Elevators can be enclosed, can have railings or low walls, or may simply be treacherous floating platforms.

Ladders: Whether free-standing or rungs set into a wall, a ladder requires a DC 0 Climb check to ascend or descend.

Shifting Stone or Wall: These features can cut off access to a passage or room, trapping adventurers in a dead end or preventing escape out of the dungeon. Shifting walls can force explorers to go down a dangerous path or prevent them from entering a special area. Not all shifting walls need be traps. For example, stones controlled by pressure plates, counterweights, or a secret lever can shift out of a wall to become a staircase leading to a hidden upper room or secret ledge.

Shifting stones and walls are generally constructed as traps with triggers and Search and Disable Device DCs. However they don’t have Challenge Ratings because they’re inconveniences, not deadly in and of themselves.

Teleporters: Sometimes useful, sometimes devious, places in a dungeon rigged with a teleportation effect (such as a teleportation circle) transport characters to some other location in the dungeon or someplace far away. They can be traps, teleporting the unwary into dangerous situations, or they can be an easy mode of transport for those who built or live in the dungeon, good for bypassing barriers and traps or simply to get around more quickly. Devious dungeon designers might place a teleporter in a room that transports characters to another seemingly identical room so that they don’t even know they’ve been teleported. A detect magic spell will provide a clue to the presence of a teleporter, but direct experimentation or other research is the only way to discover where the teleporter leads.

Altars: Temples-particularly to dark gods-often exist underground. Usually taking the form of a stone block, an altar is the main fixture and central focus of such a temple. Sometimes all the other trappings of the temple are long gone, lost to theft, age, and decay, but the altar survives. Some altars have traps or powerful magic within them. Most take up one or two squares on the grid and provide cover to creatures behind them.

Green Slime (CR 4): This dungeon peril is a dangerous variety of normal slime. Green slime devours flesh and organic materials on contact and is even capable of dissolving metal. Bright green, wet, and sticky, it clings to walls, floors, and ceilings in patches, reproducing as it consumes organic matter. It drops from walls and ceilings when it detects movement (and possible food) below.

A single 5-foot square of green slime deals 1d6 points of Constitution damage per round while it devours flesh. On the first round of contact, the slime can be scraped off a creature (most likely destroying the scraping device), but after that it must be frozen, burned, or cut away (dealing damage to the victim as well). Anything that deals cold or fire damage, sunlight, or a remove disease spell destroys a patch of green slime. Against wood or metal, green slime deals 2d6 points of damage per round, ignoring metal’s hardness but not that of wood. It does not harm stone.

Yellow Mold (CR 6): If disturbed, a 5-foot square of this mold bursts forth with a cloud of poisonous spores. All within 10 feet of the mold must make a DC 15 Fortitude save or take 1d6 points of Constitution damage. Another DC 15 Fortitude save is required 1 minute later-even by those who succeeded on the first save-to avoid taking 2d6 points of Constitution damage. Fire destroys yellow mold, and sunlight renders it dormant.

Brown Mold (CR 2): Brown mold feeds on warmth, drawing heat from anything around it. It normally comes in patches 5 feet in diameter, and the temperature is always cold in a 30-foot radius around it. Living creatures within 5 feet of it take 3d6 points of nonlethal cold damage. Fire brought within 5 feet of brown mold causes it to instantly double in size. Cold damage, such as from a cone of cold, instantly destroys it.

Phosphorescent Fungus (No CR): This strange underground fungus grows in clumps that look almost like stunted shrubbery. Drow elves cultivate it for food and light. It gives off a soft violet glow that illuminates underground caverns and passages as well as a candle does. Rare patches of fungus illuminate as well as a torch does.

A typical lower-story wall is 1 foot thick, with AC 3, hardness 8, 90 hp, and a Climb DC of 25. Upper-story walls are 6 inches thick, with AC 3, hardness 5, 60 hp, and a Climb DC of 21. Exterior doors on most buildings are good wooden doors that are usually kept locked, except on public buildings such as shops and taverns.

Most city buildings are made of a combination of stone or clay brick (on the lower one or two stories) and timbers (for the upper stories, interior walls, and floors). Roofs are a mixture of boards, thatch, and slates, sealed with pitch.

Rooftops: Getting to a roof usually requires climbing a wall (see the Walls section), unless the character can reach a roof by jumping down from a higher window, balcony, or bridge. Flat roofs, common only in warm climates (accumulated snow can cause a flat roof to collapse), are easy to run across. Moving along the peak of a roof requires a DC 20 Balance check. Moving on an angled roof surface without changing altitude (moving parallel to the peak, in other words) requires a DC 15 Balance check. Moving up and down across the peak of a roof requires a DC 10 Balance check.

Eventually a character runs out of roof, requiring a long jump across to the next roof or down to the ground. The distance to the next closest roof is usually 1d3×5 feet horizontally, but the roof across the gap is equally likely to be 5 feet higher, 5 feet lower, or the same height. Use the guidelines in the Jump skill (a horizontal jump’s peak height is one-fourth of the horizontal distance) to determine whether a character can make a jump.

Crowds: Urban streets are often full of people going about their daily lives. In most cases, it isn’t necessary to put every 1st-level commoner on the map when a fight breaks out on the city’s main thoroughfare. Instead just indicate which squares on the map contain crowds. If crowds see something obviously dangerous, they’ll move away at 30 feet per round at initiative count 0. It takes 2 squares of movement to enter a square with crowds. The crowds provide cover for anyone who does so, enabling a Hide check and providing a bonus to Armor Class and on Reflex saves.

Directing Crowds: It takes a DC 15 Diplomacy check or DC 20 Intimidate check to convince a crowd to move in a particular direction, and the crowd must be able to hear or see the character making the attempt. It takes a full-round action to make the Diplomacy check, but only a free action to make the Intimidate check.

If two or more characters are trying to direct a crowd in different directions, they make opposed Diplomacy or Intimidate checks to determine whom the crowd listens to. The crowd ignores everyone if none of the characters’ check results beat the DCs given above.

Corrosive acids deals 1d6 points of damage per round of exposure except in the case of total immersion (such as into a vat of acid), which deals 10d6 points of damage per round. An attack with acid, such as from a hurled vial or a monster’s spittle, counts as a round of exposure.

The fumes from most acids are inhaled poisons. Those who come close enough to a large body of acid to dunk a creature in it must make a DC 13 Fortitude save or take 1 point of Constitution damage. All such characters must make a second save 1 minute later or take another 1d4 points of Constitution damage.

Cold and exposure deal nonlethal damage to the victim. This nonlethal damage cannot be recovered until the character gets out of the cold and warms up again. Once a character is rendered unconscious through the accumulation of nonlethal damage, the cold and exposure begins to deal lethal damage at the same rate.

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 may be able to apply this bonus to other characters as well (see the skill Description).

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.

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 may be able to apply this bonus to other characters as well (see the skill description). Characters wearing winter clothing only need check once per hour for cold and exposure damage.

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. Those wearing metal armor or coming into contact with very cold metal are affected as if by a chill metal spell.

Falling Damage: The basic rule is simple: 1d6 points of damage per 10 feet fallen, to a maximum of 20d6.

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 Jump check or DC 15 Tumble 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 jumped, he takes 1d6 points of nonlethal damage and 2d6 points of lethal damage. And if the character leaps down with a successful Jump or Tumble 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 Jump skill.

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 Tumble check, so long as the water is at least 10 feet deep for every 30 feet fallen. However, the DC of the check increases by 5 for every 50 feet of the dive.

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 weight and the distance they have fallen.

For each 200 pounds of an object’s weight, the object deals 1d6 points of damage, provided it falls at least 10 feet. Distance also comes into play, adding an additional 1d6 points of damage for every 10-foot increment it falls beyond the first (to a maximum of 20d6 points of damage).

Objects smaller than 200 pounds also deal damage when dropped, but they must fall farther to deal the same damage. Use Table: Damage from Falling Objects to see how far an object of a given weight must drop to deal 1d6 points of damage.

For each additional increment an object falls, it deals an additional 1d6 points of damage. Objects weighing less than 1 pound do not deal damage to those they land upon, no matter how far they have fallen.

Heat deals nonlethal damage that cannot be recovered until the character gets cooled off (reaches shade, survives until nightfall, gets doused in water, is targeted by endure elements, and so forth). Once rendered unconscious through the accumulation of nonlethal damage, the character begins to take lethal damage at the same rate.

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 may 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).

A character who takes any nonlethal damage from heat exposure now suffers from heatstroke and is fatigued. These penalties end when the character recovers the nonlethal damage she took from the heat.

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 may be able to apply this bonus to other characters as well. Characters reduced to unconsciousness begin taking lethal damage (1d4 points per each 10-minute period).

Extreme heat (air temperature over 140° F, fire, boiling water, lava) deals lethal damage. Breathing air in these temperatures deals 1d6 points of 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. In addition, those wearing metal armor or coming into contact with very hot metal are affected as if by a heat metal spell.

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.

Characters exposed to burning oil, bonfires, and noninstantaneous 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 Reflex 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 Reflex 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 unlucky enough to have their clothes or equipment catch fire must make DC 15 Reflex saves for each item. Flammable items that fail take the same amount of damage as the character.

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 magma 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).

An immunity or resistance to fire serves as an immunity to lava or magma. However, a creature immune to fire might still drown if completely immersed in lava (see Drowning, below).

Smoke: 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.

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.

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 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. After this period of time, the character must make a DC 10 Constitution check in order to continue holding her breath. The save 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. When a character falls unconscious from this nonlethal damage, she drops to –1 hit points and is dying. In the next round, she suffocates.

Small characters consume half as much air as Medium characters. A larger volume of air, of course, lasts for a longer time.

Any character can wade in relatively calm water that isn’t over his head, no check required. Similarly, swimming in calm water only requires 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. On a successful DC 15 Swim check or a DC 15 Strength check, it deals 1d3 points of nonlethal damage per round (1d6 points of lethal damage if flowing over rocks and cascades). On a failed check, the character must make another check that round to avoid going under.

Very deep water is not only generally pitch black, posing a navigational hazard, but worse, it 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.

Any character can hold her breath for a number of rounds equal to twice her Constitution score. 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.

It is possible to drown in substances other than water, such as sand, quicksand, fine dust, and silos full of grain.

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.

Fog: Whether in the form of a low-lying cloud or a mist rising from the ground, fog obscures all sight, including darkvision, beyond 5 feet. Creatures 5 feet away have concealment (attacks by or against them have a 20% miss chance).

Rain: Rain reduces visibility ranges by half, resulting in a –4 penalty on Spot and Search checks. It has the same effect on flames, ranged weapon attacks, and Listen 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, below). 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 may 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, below). 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 Listen 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.

The combined effects of precipitation (or dust) and wind that accompany all storms reduce visibility ranges by three quarters, imposing a –8 penalty on Spot, Search, and Listen 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. However, 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 electricity damage equal to 1d10 eight-sided dice. One in ten thunderstorms is accompanied by a tornado (see below).

Powerful Storms: Very high winds and torrential precipitation reduce visibility to zero, making Spot, Search, and Listen 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 DC 20 Fortitude save or face the effects based on the size of the creature (see 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 wind.

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: One in ten thunderstorms is accompanied by a tornado.