While riding across the plains, the adventurers see a giant bombardier beetle lumbering along in the distance. When they're hiking through the mountains, displacer beasts suddenly appear on a rocky shelf above them just a dozen yards away. And when they're camped for the night in the woods, they can hear something stalking through the shadows beyond the light of the campfire, but they can't see it. Determining the distance at which an encounter begins sets the stage for combat, or any other type of encounter. The following rules are especially important for wilderness encounters. Encounter distance indoors on the other hand, usually depends on amounts of illumination available and whether the opposing sides have a line of sight to each other.
Once you've established that the PCs are about to have an encounter determine the distance at which they see the creatures (or vice versa). The PCs and monsters have a chance to spot each other at a distance, but even if they notice each other at first, they're certain to spot each other once they get closer together. Follow these steps:
- Determine vision conditions and terrain. Choose from the choices on Spotting Distance.
- If line of sight or illumination defines the distance at which the encounter occurs (as often happens indoors) start the encounter there. Otherwise, roll for spotting distance on Spotting Distance
- All creatures involved make spot Checks. Success means that creature seed the other creature or group. See Spotting Difficulty for modifiers on these checks.
- If neither side succeeds all creatures spot each other at one-half the rolled range
The circumstances that can affect the DC of a spot check (see Spotting Difficulty) are as follows:
Size: Add +4 to the base DC of 20 for each size category the creature being spotted is smaller than Medium-size or -4 for each size category larger. You can make exceptions for creatures with unusual shapes, such as a Large snake that's low to the ground and thus as hard to see as a Small creature.
Contrast: How starkly the creature's coloring stands out against surroundings. It's easy to spot a brightly colored couatl in a dark jungle and hard to see winter wolves in the snow.
Stillness: It;s harder to see creatures that are not moving.
Six or More Creatures: Groups of creatures are easier to spot, even if the creatures are smaller than Medium-size.
Moonlight: Nighttime, but with moonlight (or similar light).
Starlight: Nighttime with no moon, but a clear, starry sky (or similar light).
Total darkness: Overcast at night, or otherwise lightless
Example: Four adventurers are trekking through a light forest when the DM determines that they encounter eight trolls out on patrol. The DM rolls 3d6 10 and gets a result of 120 feet, the distance at which each group has the chance to see the other.
The DC to spot the trolls is 20 - 4 (they are Large) - 2 (six or, more creatures) = 14.
The DC for the trolls to spot the PCs is 20. Their Spot skill modifier is +5, so it's likely that at least one troll will spot the parry.
Any group that fails to spot the other group will do so automatically at 60 feet.
Hiding and Spotting
If creatures are trying not to be seen, it's usually harder to spot them, but creatures that are keeping low to avoid being spotted also are less likely to notice other creatures.
If creatures are hiding, they can only move at half their normal overland speed. They also suffer a -2 penalty on their own Spot checks to notice other creatures because they are staying low and using cover.
Instead of a base DC of 20 for others to spot them at the standard spotting distance, the DC is 25 + the hider's Hide skill modifier. The circumstance modifiers from Spotting Difficulty still apply, except for the size modifier (which is already part of the character's skill modifier). A character whose Hide ranks, Dexterity modifier, and armor check penalty total -6 or lower is actually has a lower DC than if he or she weren't hiding. In such cases, simply calculate the Spot DC as if the character weren't hiding (according to Spotting Difficulty). If a creature gets a special bonus to Hide because of camouflage, special coloring, and so on, use that bonus rather than the contrast bonus from Spotting Difficulty.
Additionally, the other creatures do not automatically spot hiding creatures at one-half the encounter distance. Instead, that is the distance at which the other creatures can make Spot checks to notice the hiding creatures. These are normal Spot checks opposed by the hiders' Hide checks.
|Smoke or heavy fog||2d4 x 5 ft. (avg. 25 ft.)|
|Jungle or dense forest||2d4 x 10 ft. (50 ft.)|
|Light forest||3d6 x 10 ft. (105 ft.)|
|Scrub, brush or bush||6d6 x 10 ft. (210 ft.)|
|Grassland, little cover||6d6 x 20 ft. (420 ft.)|
|Total darkness||Limit of sight|
|Indoors (lit)||Line of sight|
|Size||+/-4 per size category|
|Contrast||+/-5 or more|
|Stillness (not moving)||+5|
|Six or more creatures||-2|
|*+5 bonus on Spot check if the spotter has low-light vision or if he or she has darkvision that extends far enough.
**+5 bonus on Spot check if the spotter has low-light vision or +10 if he or she has darkvision that extends far enough.
***Unless the spotter has darkvision that extends far enough.
The rules for spotting creatures assume that both sides will eventually notice each other, and they simply establish, the distance at which they do so. But sometimes you want to take into account the possibility that the two groups will miss each other entirely. For example, the adventurers might spot a roaming behir at a distance and hide, hoping it misses them. They might also try to sneak past patrols when they are trying to infiltrate an enemy camp. Conceivably, two groups could even pass each other with neither ever knowing that the other was there.
To handle these possibilities, simply let there be a 50% chance that the other creatures encountered and the PCs don't get any closer but rather pass by each other, such as when one group is moving north and the other east. (Creatures following the PCs' trail, of course, always close with them.)
If you use this rule regularly, increase the chance for random encounters (since some of the encounters won't actually lead to confrontations).