Introducing the spot check
In this post, I cite “spot checks” to refer to third edition’s Spot checks, Next’s Wisdom (Perception) checks, and tests of awareness made with 4E and Pathfinder’s Perception skill.
The Spot skill and its descendents rate a character’s ability to notice something while doing other things like traveling, fighting, or resting. Before Spot entered the game, unless you searched, you noticed the things the game master decided you noticed. A thief might hide from you, but their success depended on their roll to hide, not on your ability to spot.
When the game master simply decides what the characters perceive, the game plays fine. After all, the game master adds things to an adventure to enrich the adventure. If you let the dice say that the PCs fail to catch a scent of brimstone, or fail to spot the cloud of bats erupting from the cliffside, then the game suffers.
Nonetheless, when Spot skill entered the game, game masters and designers dutifully worked spot checks into every situation. Whenever the party opened a door or topped a hill, everyone made a new round of spot checks. At some game tables, every bit of information had to be earned with a spot check.
I will explain why you should skip many spot rolls, reserving the spot check for a small number of specific circumstances.
Passive perception and taking 10
Fourth edition attempted to rein in spot rolls by introducing passive perception. In principle, a dungeon master could skip perception rolls and use the characters’ passive perception to determine just what they notice as they explore.
Passive perception extends the mechanic of taking-10. Instead of players stating that they take 10, the game master assumes it.
Passive perception avoids putting the players on alert by asking for a roll when they see nothing. And it avoids interrupting the narrative for all those rolls.
What’s not to like?
The problem with passive perception
Passive perception forces the dungeon master to do the extra work of tracking all the passive perception scores and of setting perception DCs. Typically, this extra effort only yields a process that amounts to the DM deciding in advance what the PCs will notice. Seem familiar?
Most DMs running for regular groups know the approximate perception bonuses of the PCs. If you bother to create something interesting or something that advances the adventure, would you hide it behind a DC that prevents the group from ever seeing it? Never. Not even authors of published adventures will hide things that enrich the adventure beyond the perception of a typical party.
But suppose a virtuous DM devises an adventure that gives keen-eyed parties a significantly different experience than unwary parties. The players still never know that their keen-senses paid off. The work of managing perception stays in the DM’s head, its effects unnoticed by the players, extra work, arguably for nothing.
If you would set the DC required to spot something within the reach of the PCs’ passive perception or take-10 value, then skip the DC. They spot it. The players will not ask you to show your work.
As a diceless method of resolving spot checks, passive perception falls short, but it still works as a way to set a difficulty class. More on that later.
The play value of rolling to spot
None of this means that you must always decide in advance what the players see. Random rolls can add an element to the game.
- Unpredictability makes role-playing games interesting, mainly for the game master. The printed adventure cannot surprise the GM. Only the players actions and the random luck of the die add surprises to the game.
- Randomness helps the game master keep some distance from the characters’ fates. The players should see the course of the game determined by their choices and by the luck of the die, not by the GM’s whims and mood.
Ask for spot checks (a) when success is uncertain, and (b) success hinges on keen senses in the game world.
Group perception checks almost always succeed
The outcome of group perception checks is rarely uncertain enough to merit a check.
Anytime every player can attempt a spot check, someone will succeed. Suppose a party of five adventurers, all with +0 to their check, passes something that requires a spot DC of 15, what D&D Next considers a moderate DC. If one person rolls, the chance of success is 30%. If everyone rolls, each has a 30% chance of success, which means the odds of someone succeeding grows to 83%. This supposes that no one is particularly good at spotting—everyone has a +0. One alert character pushes the chance of success closer to 90%.
When the odds of everyone missing something amounts to a rare fumble, does stopping the action to roll make sense? With some groups, absolutely. In particular, younger players love to roll, so group rolls create excitement despite the minimal chance of failure. Let them roll.
For most groups, you can consider any ordinary group perception check an automatic success. Skip the pointless activity, tell them what they see, and move on.
When you devise adventures, never mistake a group perception task difficulty for a challenge. On the rare occasions a group fails to spot something, they fumbled. This certainty is not a bad thing. In most cases you want the players to spot the “hidden” things in your adventure, either because these interesting things enrich the adventure, or because they advance the plot.
Hard checks change the equation. These checks impose DCs so high that only one or two members of the party can even hope to succeed. That’s the water elemental stirring the reeds under the bridge, or the key glimmering below the school of silvery fish. In these cases, allow a roll. You must be comfortable with the likelihood that no one will spot the ambush or the key.
If your players have become accustomed to calling for group perception checks, you can tell them not to waste their time, or you can let them have their fun, knowing that their success is virtually certain.
Individual perception checks may merit a roll
Of course, many spot checks can only be attempted by a character or two. This gives you a chance to add an element of uncertainty, and gives your players a potential reward for investing in perception.
Sometimes a spot task may be limited to the characters…
- leading the party in marching order.
- with darkvision or another requisite ability
- spending an action the heat of battle to look
- with applicable talents such as the ability to spot traps or arcane phenomena
- taking the role of lookout
The D&D Next exploration system turns some of these limitations into specific rules: “When a character chooses to keep watch as an exploration task, the character makes a Wisdom (Perception) check to detect hidden creatures and an Intelligence (Search) check to detect hidden objects (such as traps and secret doors) as the group travels during the current exploration turn.”
D&D Next writes this as a rule, but it applies to other games too. In many situations, only a few members of the party can make perception checks. Their skills pay here. Keeping watch is a task akin to mapping or tracking.
Group perception checks guarantee success, so individual checks like these represent a chance for players who invested in perception skills to reap benefits.
Even if only one or two characters can possibly notice something, you might ask all the players to make the roll, and then only consider the checks from those able to notice. This avoids giving clues about, say, the location of the breeze coming from the unseen exit.
Favor search over spot
Before you ask for a spot check, consider whether a search makes more sense. In most cases, this comes down to the circumstances, see “Choosing which type of perception check fits a situation.” Sometimes, you may be tempted to give someone a chance to spot something hidden, but hypothetically visible to spot. Favor making the players search. Searching plays better than spotting for a couple of reasons:
- Searching engages the characters in action, forcing them closer for a look.
- Searching invites the players to make decisions about when, where, and how to search, and how much time to risk.
If someone steps into a room, aces a die roll, and sees the key at the bottom of the fountain and the odd scratches on the floor behind the chest, you have replaced the interaction and decision making demanded by a search with an abstract roll.
Hiding and sneaking
When one creature attempts to hide from others, do not ask for spot or listen checks. Instead, use passive perception or take-10 scores to set the DC to sneak or hide. Pit the active creature’s stealth check versus the highest applicable take-10 score. In the case when a group could roll to spot, this method makes hiding possible, because group perception checks virtually always succeed.
In combat, if someone chooses to look for a hiding creature, they can spend an action and roll versus the hiding creature’s check. In Pathfinder and 3E, active looking takes a move action. In 4E, active looking takes a standard action.
The same system works for ambushes. If someone hides to ambush, they roll to hide. Later, when the ambush springs, compare the hide check against the highest passive perception or take-10 score of the targets.
While this procedure may not follow your game’s written rules, it makes sense because the targets of the ambush are busy traveling and, by default, taking 10 on perception.
Five questions to ask before calling for a Spot check
The game master almost always asks players to make spot checks, except when players take an action in combat to look for something.
As a game master, before you ask for a check, consider these five questions:
- Is something sneaking or hiding? Skip the spot check. Instead, use the party’s best take-10 (passive perception) scores to set the DC for the hide or sneak attempt.
- Can the thing to spot be noticed from the character’s vantage? If not, wait for the players to search.
- Does noticing something fall within the take-10 value of the most perceptive PC? Do not roll. Something is noticed.
- Does everyone in the party have a chance to notice something? Do not roll. Something is noticed.
- Are only one or two characters in position to notice something? Ask for a perception check.
Next: How to run an ambush
I agree with you in almost everything, but, are you considering in a ambush situation to take 20 from the ambusher? Usually when you prepared an ambush you use to have enough time to do it, so for me that is enough to have a 20+hide plus distance modifiers as DC for spot (of course, only a player that are actively searching for an ambush have a chance or rolling, the rest use his passive perception value, even in 3th edition), if not it’s almost impossible to make an ambush!
Your suggestion for how to run an ambush really makes me think. Ambushes succeed or fail—mostly fail—based on who the GM asks to roll checks. With the rules as typically interpreted, and groups of 4, the spotters all get a roll to spot and enjoy a sort of 4x advantage over the ambushers, who suffer a 4x disadvantage to hide. Your solution to the problem offers some advantages over the method I proposed.
I found this method when the players were the ambusher not the ambushed (Imagine and ambush to a column of one hundred zhentarim, roll 100d20??!! OMG noooo…) Only the watchers of the army roll vs the worst player’s hide plus 20. In this way even a full armored player has a chance to find a place to hide. Obviously if the “passive perception” of the watcher are high enough to overpass the hide+20 (plus armor penalty) of the worst sneaky player (or npc) the ambush fails without a roll. If that works for players, why not for the oposite side?
On the other hand, it’s nice you like my reach to the topic. I read your blog for longtime but never write on it, but I found most of your ideas very closed to my approach to be DM… 🙂
My players often have to roll to determine if another player is keeping something from them. In this case, your rule 5 covers it well.
Good point. If members of a party sometimes keep secret information from each other, sometimes the GM must take one or two members aside to share information. Even with the most cooperative party, I occasionally like to take members aside to share something. They may immediately return to the table and repeat everything, but the rest of the party cannot know for sure, and the process adds a delightful hint of intrigue.
Great post and clears up many of my questions regarding spot checks and surprise while exploring. What’s your opinion on using the “awareness” checks for PC’s and monsters during dungeon exploration?
I found your question about “awareness” in the dungeon thought provoking, because I tend to take the easy route, and you made me wonder if I am skipping something that could enrich my game. I tend to assume the monsters and party become aware of each other when someone enters the room. I rarely award surprise, especially in 4E, where it combines with encounter powers to turn fights into one-sided romps. Sometimes the players find themselves trying to sneak around, and then the monsters’ awareness becomes important. Mostly though, dungeon awareness falls with light and vision among aspects of the game that get (too?) little attention at my table. I don’t think I’m alone in this. When I reviewed the rules for surprise and encounter distance, earlier editions of the game tended to give the topic a few columns, while Pathfinder and 4E largely ignore the subject.
I would be interested in learning about your experience, and others’ experience, with awareness, surprise, and so on in a dungeon.