An encounter that occurs in a small, bare dungeon room is hard to make memorable, no matter what the monsters in it are doing. To maximize the fun for everyone around the table, follow these guidelines when crafting the chambers, caverns, or battlefields for your encounters.

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INTERESTING AREAS

Your first consideration in crafting interesting encounter spaces is the size and shape of the room or encounter area and the placement of the monsters and players characters. Room to Move: Make sure everyone has enough room to move around. For most encounters, the minimum is an area roughly 8 to 10 squares on a side (which happens to be the size of the largest D&D Dungeon Tiles). For an important encounter, consider a space as large as 16 or 20 squares on a side (two of those 8-square-by-10-square dungeon tiles). A postersize map like those included in DUNGEONS & DRAGONS Miniatures starter sets and in D&D adventures covers an area roughly 20 by 30 squares and makes a great area for a climactic battle. Folded in half (at about 15 by 20 squares), it also works well for other important fights. Bigger Creatures Need More Space: Large and Huge creatures need more space. An encounter that includes Large monsters needs at least 16 squares by 10 squares. With Huge monsters, the encounter area should be at least 20 squares by 20 squares (or about three large D&D Dungeon Tiles). Gargantuan monsters work best on poster maps. Avoid Symmetry: Symmetry is boring. Fighting in one square or rectangular room after another is dull and doesn’t allow for much tactical variety. Let rooms branch out into corridors, alcoves, and antechambers, and find ways to draw some of the fighting into these areas. Also, build rooms using all three dimensions. Large platforms and raised areas, depressions and pits, along with galleries and overlooks, are interesting and can produce fun tactical situations. Fantasy It Up: Your goal is not to create a realistic area for your encounter. Sprinkle fantastic features liberally throughout your encounters, and every once in a while put in fantastic features of cinematic scope. A room where the PCs have to jump between floating platforms as they fight a wing of gargoyles, or avoid gouts of magma while fighting for their lives against a red dragon—those are encounter areas that take on a life of their own. They reinforce in everyone’s mind that D&D is a fantasy game. Encounter Distance: For outdoor encounters, start the characters 10 squares away from the monsters. If terrain or visibility suggests a short-range encounter (dense forest or thick fog, for example), use 5 squares instead. In wide-open areas, such as rolling hills or farmland, use 20 squares. In open terrain, characters might see monsters at even greater distances, which gives them a chance to try to avoid an encounter entirely (especially if the monsters don’t see them). Don’t start an outdoor encounter with either the characters or the monsters at the edge of the map. Leave room for everyone to move around, which for some characters often means getting away to a safer distance from the monsters.

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TERRAIN FEATURES

It’s easy to overlook the effects of terrain when building adventures and encounters. After all, the party’s enemies are the monsters, not the dungeon stairs, the low rock wall, or the crumbled statues in the dungeon room. Yet, terrain provides the context for an encounter. A mob of goblin archers is easy to defeat when only empty terrain lies between it and the party. Take the same goblins, put them on the opposite side of a wide chasm, and the characters face a much tougher challenge.

TYPES OF TERRAIN FEATURES

✦ Difficult Terrain: It costs 1 extra square of movement to enter a square of difficult terrain.

✦ Blocking Terrain: Blocking terrain prevents movement, blocks line of sight and line of effect, and provides cover.

✦ Challenging Terrain: Challenging terrain requires a skill check or ability check to successfully cross it.

✦ Hindering Terrain: Hindering terrain prevents movement or damages creatures that enter it.

✦ Obscured Terrain: Obscured terrain provides concealment and blocks line of sight if a target is far enough away from you. However, it has no effect on movement.

✦ Cover Terrain: Cover terrain provides cover (see page 43), making ranged attacks more difficult.

Difficult terrain slows down characters without blocking line of sight. In encounter design, difficult terrain is a useful tool to make a path less appealing without removing it as an option. It gives you some of the benefits of walls and other terrain that blocks movement without the drawback of constricting the party’s options. It costs 1 extra square of movement to enter a square of difficult terrain. Too much difficult terrain proves frustrating, since shifting and attacking becomes impossible. Use difficult terrain in small quantities. The ideal patch of difficult terrain is just big enough to force the characters to spend an extra round moving down a particular path or taking a position in an encounter area. Avoid using much, if any, difficult terrain in areas where you expect the PCs and monsters to fight in melee. Difficult terrain prevents shifting, which can turn a melee into a static slugfest. That might make for an occasional change of pace, but it makes the game boring if it happens too often. Examples: Rubble, uneven ground, shallow water, fallen trees, a steep slope.

Blocking terrain prevents movement and blocks line of sight. The characters might be able to use the Athletics skill to climb over such obstacles, but otherwise this type of terrain prevents movement. Blocking terrain channels the encounter’s flow and cuts down on the range at which the PCs can attack the monsters (and vice versa). Using blocking terrain, you can present two or three distinct paths in an encounter area and different challenges down each one. For example, the characters come under attack when they enter an intersection. Orc warriors charge down two corridors, while an orc shaman casts spells from a third. If the PCs charge the shaman, they risk attack from two sides. If they fall back, they can meet the warriors along one front, but the shaman is safely away from the melee. Don’t use too much blocking terrain. Fights in endless narrow corridors are boring. While the fighter beats on the monster, the rest of the party must rely on ranged attacks. Examples: Walls, doors, impassable rubble.

Challenging terrain requires a skill check or ability check to cross. Fail the check, and something bad happens to you. Challenging terrain makes skills more important. It adds an active element of risk to the game. Athletics checks and Acrobatics checks are often required for challenging terrain. Moving across slick ice requires Acrobatics. Slogging through deep mud requires Athletics. Running over a thin beam requires Acrobatics. Use the Skill Check Difficulty Class table below to select a relevant DC for the party’s level. A successful check allows a character to move at his speed across the terrain. Some challenging terrain is also difficult terrain. The type of terrain determines what happens when characters fail their checks. Climbing characters might fall. Characters wading through mud must pay 1 extra square of movement to enter the square. Characters moving across ice fall prone in the first square of ice they enter. Too much challenging terrain wears down the party or slows the action if the characters have a few unlucky skill checks. If the terrain has a high DC or if the characters are cautious, they can treat it as hindering terrain (see below) instead. Examples: Ice, deep water, deep mud, thin beam across a chasm.

Hindering terrain prevents movement (or severely punishes it) or damages creatures that enter it, but allows line of sight. Hindering terrain can be interesting because it encourages ranged attacks. You can shoot an arrow over hindering terrain, while it is impossible or risky to run through it to attack in melee. Too much hindering terrain makes melee characters and monsters worthless. It is best used to protect a monster or two, or as a favorable defensive position that the PCs can exploit. Examples: Pits, deep water, lava, fire.

Obscured terrain provides concealment and blocks line of sight if a target is far enough away from you. However, it has no effect on movement. The following rules expand on the material found in Chapter 9 of the Player’s Handbook.

OBSCURED TERRAIN

✦ Lightly Obscured: Squares of dim light, fog, smoke, heavy snow, or rain are lightly obscured. Concealment: A creature has total concealment against you if 5 or more lightly obscured squares stand between you and it (including the nearest square of the creature’s space). Closer creatures have concealment, but not total concealment. Vision: You can see through lightly obscured squares, but you take a –5 penalty to Perception checks to see or spot things.

✦ Heavily Obscured: Squares of heavy fog or heavy smoke are heavily obscured. Concealment: Adjacent targets have concealment against you. Out of Sight: You can’t see creatures that are not adjacent to you. Vision: You can see 1 square away, but you take a –5 penalty to Perception checks to see or spot things. You can’t see squares farther away.

✦ Totally Obscured: You can’t see at all. You can’t see any creature, not even those adjacent to you.

Obscured terrain lends a sense of mystery to an encounter. The characters can’t see what lurks ahead, but their enemies have open space they can move through to attack. It restricts ranged attacks similar to blocking terrain does, but it allows more movement. Encounters are a little more tense and unpredictable. Obscured terrain becomes a problem when it shuts down the fight. The characters likely stick close together, and if the monsters can ignore the concealing terrain due to some magical effect, the fight might be unfair rather than tense. Examples: Fog, mist, zones of magical darkness.

Cover terrain provides cover, making ranged attacks more difficult. See “Cover” in Chapter 3 on page 43. Cover terrain forces ranged attackers to move if they want to shoot around it. It also helps creatures avoid ranged attacks. Too much cover makes the encounter too difficult for ranged attackers. Examples: Low walls, piles of rubble.

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TERRAIN AND ROLES

Monster roles provide the best pointer for how to use terrain. Each role has different preferences for the terrain it thrives in. When you build an encounter, think about the monsters you want to use and how terrain can help them. The Natural Method: It makes logical sense that creatures seek out favorable terrain. If you create an area map first, think about how your villain would exploit the terrain by intelligently deploying his followers. Even wild animals are clever enough to utilize terrain. For example, a lion hides in wait by a spring. The spring draws thirsty prey, and it blocks many routes of escape. The Staged Method: If you build encounters purely with an eye toward the game experience, start by picking out monsters, and create terrain to maximize their advantages.

These monsters thrive on wide, open spaces and difficult terrain. An open space allows them to rain attacks on the party at a distance, while difficult terrain forces melee characters to waste precious time moving to engage the artillery. Any terrain that blocks movement or slows it down without affecting line of sight is an artillery monster’s best friend. Artillery also likes having some cover nearby where it can gain some protection from the party’s ranged attacks.

Brutes and soldiers both like to get into melee while avoiding the party’s ranged attacks. They favor twisty, dense terrain that has enough room for melee, but makes it difficult for ranged attackers to get in shots from a distance. Brutes and soldiers also like choke points that make it difficult for rogues and other strikers to get behind them.

Controllers like the same sort of terrain as brutes and soldiers, but with one key difference: A controller likes slightly larger spaces where its allies can take advantage of its attacks. If an area is too narrow, a controller and his soldier buddies can’t both attack the party. Controllers like wide spaces, but not necessarily long ones. Long spaces allow ranged attackers to pick off the controllers and their allies at a distance. Wide ones allow the monsters to all attack at once while keeping the action at relatively close range.

Lurkers love obscured terrain and areas thick with blocking terrain. They usually need cover to hide from the PCs or to escape out of the party’s reach. However, lurkers also like wide corridors and areas that give them lots of approaches to the characters. A lurker wants to slip past the party’s defender, making narrow passages and easily controlled chokepoints bad for such a monster.

Skirmishers are a little like lurkers in that they want open spaces to attack the party from multiple directions. On the other hand, if the terrain is too open, skirmishers can’t easily evade the party’s attacks. The ideal skirmisher terrain is a mix of blocking or obscured terrain and open terrain, such as a series of linked dungeon rooms. A skirmisher can attack in one room, then slip around the corner to a nearby room to prepare its next strike.

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BUILDING AN ENCOUNTER SCRIPT

Terrain and monsters never combine in a vacuum. The characters’ abilities and tactics, the encounter’s purpose in the overall adventure, and the goal of the encounter all play a role in determining the right terrain for an encounter. An encounter script in your mind, a simple walk-through of the encounter, is a great tool for figuring out how to add and use terrain. Building an encounter script is a simple process. Start with the basics of the encounter area. You might have the monsters picked out or the area mapped, depending on how you have designed the area. With either of those factors in mind, walk through the likely outcome of the encounter. Suppose that the main villain in your adventure is a wizard and his four ogre bodyguards. Looking over the wizard’s spells, you see that he has lots of area of effect attacks. The four ogre bodyguards are brutes. Assume that the party fights these monsters in a huge, featureless room. It might help to break out a grid and miniatures, so you can better visualize what happens. The characters who excel in melee run forward to attack, while the ogres move to intercept them. The ranged characters hang back and try to take out the wizard. Meanwhile, the wizard uses his area attacks. Run the fight in your head, looking at it from the characters’ and the monsters’ points of view. Consider likely tactics and goals the PCs have, and then do the same for the monsters. What kinds of actions can you expect both sides to take? How does each side respond to the other? Answer these questions with an eye toward making things easier for the monsters and harder for the PCs. A few points become clear:

✦ The wizard has trouble using area attacks against PCs who are in melee with the ogres. He can blast the PCs, but he might also catch his minions in the attack.

✦ The ogres need enough room to crowd around the party, but if the room is too spacious, the PCs can run around the ogres and attack the wizard.

✦ The wizard needs cover for protection against ranged attacks, or the ogres need some way to threaten such PCs. Run down your list of concerns, and think of how you can use terrain to respond to each of them. Here are some potential complications you can add:

✦ The ogres need to spread out, so be sure to add lots of open space for them to maneuver.

✦ Alternatively, you could give them a path that lets them maneuver around the party. For instance, the passage leading into the encounter area loops around to the east and west. The ogres wait where the two entrances meet, and two of them rush down whichever passage the PCs don’t use.

✦ In contrast, the wizard wants only a narrow path to her position. Hindering terrain, such as a short bridge over a pit, restricts access to the wizard. Best of all, one of the ogres can take up position here and force the PCs to fight through it. One spot of hindering terrain should be enough.

Creating a script is an iterative process. Keep walking through the scenario, thinking of how the PCs and monsters might act in response to the terrain that solves the problems you foresee, until you have just the right balance of challenge and complication. In the example above, walk through the encounter again, injecting the terrain elements mentioned above. Does the encounter feel fun? What other elements do you want to add?

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GETTING TERRAIN MIX RIGHT

Dressing up an encounter with terrain is an art, not a science. Only during and after an encounter, when you can see if it worked the way you wanted, can you judge if your decisions were good ones. Experience is your best guide. Keep the following points in mind to try to use terrain well. 1. Terrain has a purpose. Some terrain is just supposed to look cool. Some terrain serves to slow down the party. Look at each section of the encounter area and make sure it fulfills some purpose. 2. Terrain encourages choices. Do the PCs fight the goblins coming down the corridor, or do they focus on the bugbear torturer? If every fight has the PCs on one side of the room and the monsters on the other, things get boring fast. Build areas where the PCs and monsters can take a lot of different paths to attack each other. 3. Terrain encourages movement. A crumbling wall provides cover against a beholder’s attacks. An ogre runs to close a portcullis, trapping the PCs in the dungeon unless they can intercept it. Terrain should give characters and monsters a reason to move toward it or away from it. An easily defended position, such as a narrow doorway, is a magnet for the PCs if they are outnumbered. On the other hand, if the PCs outnumber the monsters, they want to push the fight to an open space. If both sides are standing around trading blows round after round, your terrain isn’t doing its job. 4. Terrain makes fights more interesting. After an encounter, the players should remember the terrain as well as the monsters that occupied it. Part of this memorability comes from the terrain’s tactical aspects, but your description also plays a big role. Search for reasons to add memorable terrain to the battlefield. Using generic rubble as terrain is useful, but you can add to the experience by describing the rubble in a temple to Torog as heaps of ancient, broken skulls. That terrain has the same mechanical effect as ordinary rubble but injects an element of creepiness into the atmosphere.

 

SAMPLE MUNDANE TERRAIN

Difficult terrain might take the form of a steep staircase in a dungeon or shifting sands on a stormy beach. This section offers help in applying the basic terrain categories to the features that characters commonly find in their adventures. Terrain and Skill Checks or Ability Checks: When terrain requires a skill check or ability check, use the Difficulty Class by Level table (page 42) to set a DC that’s appropriate to the characters’ level. Some of the examples below show DCs for breaking down doors or opening locks, and also show the level at which a character should be able to break down the door with a Strength check of moderate difficulty. Thus, that level is a good rule of thumb for dungeon design. Don’t put an iron door in a dungeon designed for 10th-level characters unless you intend it to be difficult for them to break through.

Dungeon dressing is a category of mundane terrain that covers everything you expect to find in a dungeon. Walls: Most dungeon walls are masonry or carved out of solid rock. Characters can use Athletics checks to climb a wall and break right through a wall with an incredible Strength check. Doors: Opening a door takes a minor action, or a standard action if the door is stuck and requires a Strength check. A door might be locked, or it could have a window in it that provides superior cover to anyone firing through it. Characters can open locked doors by using Thievery to pick the lock instead of breaking down the door. This is a standard action as part of a skill challenge. See “Open Lock” on page 189 of the Player’s Handbook. Portcullises: A portcullis is a metal gate that swings shut or drops down from the ceiling. It provides cover, and a Strength check allows a character to lift it or pull it open. Secret Doors and Trapdoors: In the confines of a dungeon, some doors are disguised as part of the wall, floor, or ceiling. A successful hard difficulty Perception check allows a PC to spot an average version of one of these portals. They make great ambush points for monsters or hiding places for treasure. Small Statues and Pillars: These terrain features are difficult terrain that provides cover. You can move through their spaces because they are small enough to squeeze past. Big Statues and Pillars: These are blocking terrain. As a rule of thumb, a big statue or pillar completely fills one or more squares. Tapestries and Curtains: It costs 1 square of movement to move through a tapestry or curtain hung to partition a room or hallway. Tapestries and curtains block line of sight. Stairs: Stairs are difficult terrain, unless the steps are sufficiently broad or the slope of their ascent is gentle. Pools: Shallow pools, those waist-deep or less to a character, are difficult terrain. Characters must use Athletics checks to swim through deeper pools. Ladders: Characters can climb ladders without making Athletics checks. A PC moves at one-half speed when going up or down a ladder. Ledges and Platforms: Low ledges or platforms (below waist-high) are difficult terrain. Higher ones require Athletics checks to jump or climb onto.

Like characters, objects have hit points and defense scores (except for Will defense; see Object Immunities and Vulnerabilities, below). An object’s AC, Fortitude, and Reflex defense depend entirely on its size. (As you can tell from the following table, it’s pretty easy to hit an object; so easy, in fact, that many DMs just skip the attack roll unless the situation is particularly dramatic.) An object’s hit point total generally depends on two factors: its size and its material. As a rule, larger or thicker objects have more hit points than smaller or thinner ones. Objects made of stone or metal have more hit points than those made of wood or glass. Exceptions to this general rule abound. An object that’s big but full of delicate moving parts might have fewer hit points than a smaller, more solid object, because it doesn’t take as much damage to render that object functionally useless. To determine an object’s hit points, first find its size on the Object Properties table below. Then apply any appropriate multipliers based on its material or composition. If more than one multiplier is appropriate, it doesn’t matter what order you apply them in. A Large iron clockwork contraption, for instance, should have around 60 hit points (40 for Large, × 3 for iron, × 0.5 for intricate construction). An object reduced to 0 hit points is destroyed or otherwise rendered useless. At your judgment, the object might even still be more or less whole, but its functionality is ruined—a door knocked from its hinges or a clockwork mechanism broken internally, for example.

Usually, it doesn’t matter what kind of attack you make against an object: Damage is damage. However, there are a few exceptions. All objects are immune to poison damage, psychic damage, and necrotic damage. Objects don’t have a Will defense and are immune to attacks that target Will defense. Some unusual materials might be particularly resistant to some or all kinds of damage. In addition, you might rule that some kinds of damage are particularly effective against certain objects and grant the object vulnerability to that damage type. For example, a gauzy curtain or a pile of dry papers might have vulnerability 5 to fire because any spark is likely to destroy it.

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OUTDOOR TERRAIN

From a dense forest to a scorched desert, the characters face a wide variety of outdoor terrain. Trees: Trees are difficult terrain that provides cover. Big trees are blocking terrain. Undergrowth: Low, thick trees, small plants, and other undergrowth are difficult terrain. Foliage, Leaves, and Vines: Screening foliage, leaves, and vines are all concealing terrain if the plant material hangs down low enough or projects outward enough to block sight. Such plant matter might also be difficult terrain if the branches are thick or difficult to move through. Sand and Dirt: Soft, shifting sand or dirt is difficult terrain. Hard-packed sand and dirt is normal terrain. Hills: A slope is difficult terrain, though shallow or gentle slopes are normal terrain. Ice: Slick ice patches are difficult terrain. You might also require an Acrobatics check for a character to avoid falling. See the relevant DCs under “Balance” in the Acrobatics skill in the Player’s Handbook (page 180). Swamp: Swamp is a combination of shallow pools and mud. It is difficult terrain.

Fortifications are built to repel attacks, giving you a lot of interesting terrain options. Streets: The best maintained streets are normal terrain, but potholes and poor maintenance in the rough parts of town can make them difficult terrain. Windows: Windows provide line of sight and grant cover. Opening a window is a minor action, and moving through one large enough for a creature to fit itself through costs 1 extra square of movement. Arrow Slits: Arrow slits are small holes designed to provide archers with maximum protection while they fire. An arrow slit grants a ranged attacker superior cover while granting him or her a clear view of the battlefield. The firer determines the target’s cover from the square just outside the slit. Murder Holes: Murder holes use the same rules as arrow slits, except that they are placed in the ceilings of chambers to allow archers above to rain fire on attackers below. Catwalks: Narrow catwalks are difficult terrain. You might also require an Acrobatics check to avoid falling. See the relevant DCs under “Balance” in the Acrobatics skill in the Player’s Handbook (page 180). Furniture: It costs 1 extra square of movement to move on top of a table or chair, but no extra movement to move off. A character can also crawl beneath a table, gaining cover against standing foes.

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LIGHT SOURCES

Many dungeons and caverns are illuminated to some degree, since only a few monsters are truly at home in pitch blackness. The Example Light Sources table lists light sources, both mundane and magical. (It expands on the table in the Player’s Handbook, page 262.) The table describes the radius (in squares) of the light, the brightness, and the duration of the light effect. You can alter these numbers as you see fit in the context of a specific terrain you make. The last entries on the table show the light emitted by fire creatures—fire elementals, hell hounds, or immoliths, for example. Only creatures made of fire (which includes most creatures that have the fire keyword) shed this much light.

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VISION AND SPECIAL SENSES

Many creatures see in the dark much better than humans do. Some creatures even see in complete lightlessness. Other creatures get along in the dark by using other senses—uncanny hearing, sensitivity to vibrations and air movement, or an acute sense of smell. Normal Vision: Creatures that have normal vision see normally in areas of bright light. Areas of dim light are lightly obscured. Areas of darkness are totally obscured. Low-Light Vision: Creatures that have low-light vision see normally in areas of bright and dim light. Areas of darkness are totally obscured. Darkvision: Darkvision lets creatures see normally regardless of light. Blindsight and Tremorsense: Creatures that have blindsight or tremorsense ignore obscured squares or invisibility within range. They can see creatures in range regardless of these conditions. Beyond that range, they rely on vision (unless they’re blind).

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SAMPLE FANTASTIC TERRAIN

The D&D world is rife with magic, and this power spawns wondrous terrain. Massive spiderwebs choke ancient passages. Elemental energy surges through a cavern, granting strength to fire-based spells. Tier and Skill Checks and Ability Checks: Throughout these examples, the term “per tier” is used to show how an effect should scale. Multiply the per tier value by one for heroic tier, two for paragon, and three for epic. If a terrain feature grants a +1 bonus to attack rolls per tier, the bonus is +1 at heroic tier, +2 at paragon tier, and +3 at epic tier. Terrain scales in order to keep it relevant as PCs and monsters gain higher attack bonuses and hit points. It is an element of game balance and a reflection of the greater magical power present in paragon or epic locations.

The site of ceremonial sacrifices, a great slaughter, or some other calamity, the spirit of death hovers over blood rock. A creature standing in a square of blood rock can score a critical hit on a natural die roll of 19 or 20.

This thin, blue slime is harmless but extremely slick. A creature that enters a square filled with cave slime must succeed at an Acrobatics check or fall prone. Use the Difficulty Class by Level table (page 42) to set a DC that’s appropriate to the character’s level.

Choke frost is found in the deepest caves of the distant north or in the lairs of creatures of elemental ice. This light, white mist congeals into thick ice as creatures or other sources of heat move through it. Each time a creature enters a square of choke frost, it takes a –1 penalty to speed. As a move action, a creature can negate this penalty. Creatures that have the cold keyword are immune to this effect.

These strange, Underdark mushrooms are normal terrain, but as soon as a creature enters a square of these mushrooms, the mushrooms create a thick cloud of spores. The square provides concealment (see page 281 of the Player’s Handbook) for 5 minutes. Once a square has discharged a cloud, it cannot do so again for 24 hours.

This strange Underdark moss is a useful ingredient in creating everburning torches and sunrods. It is highly flammable and burns bright. A character in a square with ember moss takes an extra 5 damage from all fire attacks and takes a –4 penalty to saving throws to end ongoing fire damage.

Due to planar energy, the presence of a powerful artifact, or some other factor, this terrain boosts certain kinds of attacks. Pick one power keyword, such as fire, charm, or arcane. Attacks that have that keyword gain a +5 bonus per tier to damage.

This thick, tough grass grows in deep forests of the Feywild or in areas where the Feywild’s magic filters into the material world. A creature that falls prone in a square of grab grass must make a Strength check to stand up. Use the Difficulty Class by Level table (page 42) to set a DC appropriate to the character’s level.

This black, viscous goo feeds on Underdark insects and vermin by trapping them in place and slowly digesting them. It poses no threat to larger creatures, but its clinging substance can cause a creature to become stuck. Grasping slime is difficult terrain. Use the Difficulty Class by Level table (page 42) to set an Athletics DC appropriate to the character’s level to pass through the slime. On a failed check, the creature enters the slime, but its move ends immediately.

Illusions can mimic any terrain. Creatures that realize that an object is an illusion ignore its effects, while those that do not realize the truth behind the illusion react to it as appropriate. Use characters’ passive Insight checks to determine if they notice something “not right,” but don’t allow them to make active checks without good reason. Once a character has reason to be suspicious, he can make an Insight check as a minor action to attempt to disbelieve an illusion. Use the Difficulty Class by Level table (page 42) to set a DC appropriate to the character’s level and the relative difficulty you wish to assign to disbelieving the illusion. Illusions don’t do any actual damage, and interacting with them might reveal their true nature. For example, a character who walks into an illusory pit doesn’t fall to the ground. At that point, the character realizes the pit is fake.

An illusory wall blocks line of sight. Creatures can walk through it without penalty, though obviously creatures that believe the illusion aren’t likely to try doing so. Some illusory walls are similar to one-way mirrors in that they are transparent from one side (allowing a viewer to see creatures on the other side) while from the other side they appear to be normal walls (blocking line of sight, and looking like normal wall terrain).

This strange rock dramatically increases the weight of all objects. It is difficult terrain, and ranged attacks that trace line of sight through it take a –2 penalty to attack rolls.

Mirror crystal causes strange twists and turns in space. A creature standing on mirror crystal can look down and see all the other mirror crystal spaces within 20 squares. Creatures can make ranged attacks through mirror crystal, targeting any creature on or adjacent to another square of mirror crystal. The range to a creature attacked through mirror crystal is 1 square.

This tall stone pillar is infused with life energy. Any creature that begins its turn adjacent to it regains 5 hit points per tier.

A sacred circle is dedicated to a specific deity and infused with divine energy. A creature that shares that deity’s alignment gains a +2 bonus to attack rolls while standing in the circle. A sacred circle typically fills an area 3 squares by 3 squares.

A slide is coated with a slick substance and designed to send characters tumbling, offering quick transport at a price. A slide is difficult terrain. A character who enters a slide square must make an Acrobatics check. Use the Difficulty Class by Level table to set an Acrobatics DC appropriate to the character’s level. A creature that fails immediately moves to the end of the slide, falls prone, and ends its move.

The webs of giant spiders are difficult terrain. A character who enters a spiderweb must make an Athletics check or Acrobatics check or become immobilized. Trapped creatures can use the escape action to free themselves from the web. Use the Difficulty Class by Level table (page 42) to set an appropriate DC for the characters’ levels. Spiderwebs also provide concealment.

Teleporters are magical gates that whisk characters from one spot to another. A creature that enters a teleporter’s space immediately moves to the teleporter’s destination square. The square can be another teleporter to allow for two-way travel. In that case, the creature automatically moves adjacent to the destination teleporter.

Whirlwinds form in areas infused with elemental energy (often in water or air). A whirlwind’s current pulls creatures along its path. This is a slide effect. A creature that enters a whirlwind moves a distance and direction determined by the strength of the whirlwind. An affected creature can fight against the wind by spending squares of movement to reduce the distance the wind slides it. Only one whirlwind square can affect a creature at a time. If the wind slides the creature through or into another whirlwind square, that square has no effect. A whirlwind can also move creatures upward. A creature that ends its turn outside of a whirlwind square and aloft falls to the ground (if it is not flying—see “Flying,” page 47).