by Mike Mearls

In Part One of "Setting the Stage," we discussed how to use cover and blocking terrain to construct interesting and fun encounters for your campaign. This week, let's turn our attention to concealment, perhaps the most vexing environmental effect that you can throw at your players.

Nothing's more frustrating than having a +19 attack against a puny kobold come up with nothing but air because of smoke, fog, or some other concealing effect. Concealment also has a very cool secondary effect: It blocks sight, but it has no effect on movement. The characters can't see what's coming, but whatever's on the horizon can move to attack them without concern. Thus, concealment can turn the simplest encounter into a tense struggle. The characters' attacks may miss despite their skill and tactics, while opponents can pounce upon them with little or no warning.

Using concealment in your encounters takes a good deal of careful planning. This article discusses some of the challenges associated with its use.

In an area with concealment, how often you attack becomes almost as important as how well you fight, if not moreso. Creatures with many attacks, or mobs of many creatures, tend to have an advantage over the party. In most groups, only one or two characters have a good attack bonus or the hit points and Armor Class to wade into a direct confrontation with an opponent. Spellcasters who rely on touch attacks, either ranged or otherwise, might end up blowing spell slots on missed concealment checks. Characters who rely on ranged attacks are particularly hurt, since concealment may make attacks beyond a few squares away impossible.

Given the penalties the characters must cope with, it is relatively easy to cast concealment as an asymmetrical condition. Monsters with blindsight or similar abilities can ignore concealment. Not only do their attacks function as normal, but they can maneuver without restriction. Since they can't see far ahead, the characters must move forward cautiously. Meanwhile, the monsters can set up traps, prepare ambushes, and make similar preparations. If you really want to give the party a headache, set a spellcaster with blindsight against them. While fireballs and magic missiles hammer them from beyond a cloud bank, they can do little but guess at their opponent's location.

Terrain and Concealment
Low walls, pits, and other mundane obstacles become much more daunting in an area filled with fog or magical darkness. Since the party members cannot see the terrain, they have no way of planning on attack or preparing for their opponents' tactics. The characters might blunder into a bramble bush, tumble into a hole, or fall down stairs that they simply didn't see. If the monsters can see through the concealment without penalty, this situation becomes even worse.

In many cases, an encounter that uses concealment may benefit from less, rather than more, terrain. If the party cannot see but the monsters can, the monsters can use spells and ranged attacks without fear of a counter-strike.

Stunts, Maneuvers, and Concealment

With The Book of Iron Might, the players (and DM) can make use of maneuvers and stunts. (For more on maneuvers, see our online preview.) Concealment affects maneuvers like any other attacks, making them just as risky as standard strikes. Of course, we could always use a new maneuver effect to take care of that:

Accurate Strike (Intelligence, Wisdom)

You take careful focus with your attack, lashing out only if you are sure you have an opponent before you. This maneuver requires you to take a few passive, tentative strikes. The penalty reflects your chances of making an ineffectual attack, or perhaps not making one at all, as you hold your strike for too long.

Prerequisite: None.

Rules: You ignore any concealment your opponent gains against your attacks.

Penalty: You suffer a -10 penalty to attack rolls against a creature with concealment (25 percent miss chance), and a -20 penalty to attack rolls against a creature with full concealment (50 percent miss chance).

Ranged Attacks: You can use this maneuver effect with a ranged attack, but the target must be within 30 feet, and you must be able to see him.

Special: You can use this ability only against creatures that have concealment. You cannot use it against targets that gain a miss chance due to other abilities, such as incorporeal.

When it comes to stunts, there isn't much you can do that is specific to an area with concealment. If you run a game that features a lot of stunts and crazy, movie-style action, you might want to give a character a bonus to any stunt in such an environment. After all, a leap over a stone wall is much more dangerous if you can't see what's on the other side.

Did you catch Part One of this article?