It must be understood that combatants who are standing guard or moving forward with a conscious awareness of potential threat are not required to roll surprise when encountering the enemy. The chance for surprise only exists where a combatant may legitimately feel a sudden wonder or astonishment. This may occur due to a number of circumstances, too many to fully describe here; but the most common ones are listed below. The attackers are,
- . . . travelling a great distance over the course of a long day, so that if there is no reason to suppose that there may be an ambush being made ready ahead, the combatant's guard is down.
- . . . moving too quickly to properly assess the dangers that might lurk around a corner, so that they rush into a situation before they have time to prepare for it.
- . . . attacked in a place usually reserved for peace of mind, trade or goodwill, such as a temple, market, tavern, inn, arena, a busy city avenue, road or square, an upscale residence or a government house, or a heavily patrolled place such as the entry gate to a town or city, a fair or a military headquarters. In such places, combatants will naturally drop their guard, partly due to the number of distractions that makes it impossible to keep their guard up - this makes surprise a possibility, explaining why such areas are busy places for thieves and assassins.
- . . . busy with making camp or breaking camp, having failed to establish one person to stand guard during this time, when everyone is moving about and paying attention to details rather than what may be going on all around.
- . . . weary, injured to the point where they are in the negatives, drunk, under the influence of a spell or environmental condition, heavily muffled due to the weather, asleep or any other physical condition that would challenge their usual sharp attention.
- . . . chatting incessantly in the guise of the Players, who are paying very little attention to what their characters are doing, thus indicating that the player characters are themselves allowing their attentions to wander into minutia or frivolity.
- . . . expecting one thing and getting another. When something comes through the door, over the hill, drops down through the clouds or is stumbled upon that is so completely unusual for the place and time, then there is a reasonable chance that surprise will occur.
Surprise is therefore rolled when there is a reasonable chance that one set of combatants or the other is likely to be surprised. Surprise is rolled on a d6. One player for the party is designated by the DM to roll a surprise die for the whole player party. The DM then rolls a surprise die for all combatants opposed to the party. The two dice are then compared.
Surprise normally occurs when the die comes up a 1 or a 2. This is usually written as being surprised "2 in 6."
In some circumstances, however, an individual character may have a greater ability to avoid surprise than others. The Monk character, for example, reduces the chance of surprise with levels gained. Other characters, such as the ranger in the wilderness or the thief and assassin in an urban setting, may only be surprised on a 1 (depending on their abilities or the circumstances involved). The same is true of many creatures. Moreover, some creatures will surprise more often than usual, on a 3 in 6 or a 4 in 6, including elven or halfling characters that are acting alone. Finally, creatures with a sufficient dexterity receive a modifier to the die rolled (+1 for a 16 dexterity, +2 for a 17 dexterity and +3 for an 18 or better dexterity) or receives an adjustment from some other source (luck, spell, magic item, etc.). See the example under Initiative.
Comparing the dice can therefore be a complicated issue. Usually, however, the matter is settled when neither side rolls a sufficiently low number to be surprised. If it happens that either side is surprised, however, due to a lack of modifiers or because the creature faced has a high chance of causing surprise, then the surprised group of combatants are considered to be stunned for one round.
Note that if some members of either group of combatants have a sufficient adjustment to the die to indicate that they, personally, are notsurprised, then they are free to act in the next round, even if their companions are not. This means that they may be the only actual combatants free to attack - in which case, they would automatically win initiative, since everyone else is stunned.
It is possible for both sets of combatants (or all three sets of combatants, if the case arises) to be completely surprised, and for no one to be able to take any action. In that case, normal initiative would then be resolved to see which combatants attack first. Further, if individuals on opposing sides are not surprised while their companions on both sides are, then initiative would be rolled to resolve which of the unsurprised combatants would attack first.
See Attacking in Combat