50% Random Encounter Rules
Part of the fun of any campaign that involves travel through dangerous territory is the chance of a random encounter. Of course it is not really a random encounter when you as the DM arbitrarily decides that the party has run into one or more random monsters (which for our purposes will include hostile NPCs with class levels, whether humanoid or not). There is no allowance for the players' influencing the likelihood of being ambushed. Rather, there should be a chance for both possibilities--the encounter happens, or it does not.
The easy method is for you to roll a basic d20 and pick some "encounter DC" that corresponds to your intuitive guess about the density of population of wandering monsters peculiar to that area of your game world. You could allow the PCs some skill checks to avoid detection, but there can be multiple encounters per day/night and more than one chance to be discovered while encamped--for any given patch of terrain, the natives will know the lay of the land better than any traveler and may well trace the PCs to their location via their scents or tracks. Therefore no location (notwithstanding magical protection such as a Rope Trick or Mansion) can be 100% secure. So there should always be a nonzero chance for a random encounter, unless you judge the pacing of the campaign plot should omit the delay of the occasional random encounter.
I also think it can become tedious choose and stick with a given frequency to test for random encounters--doing an encounter check for each hour between sunset to sunrise seems like a waste of die rolls especially if you are using a high DC for ruling the encounter check a 'success' (i.e., something shows up). Moreover, repeating this process over several days' travel can be a nuisance and slow down the dramatic pace of a journey between urban waypoints. On the other hand, if you go the other way and only roll for a random encounter _per day_ of travel, you eliminate the possibility of having multiple encounters per day as a result of PCs doing rather poorly at keeping out of sight and being quiet--so did ALL the PCs somehow succeed on all their Stealth and Survival checks?
These house rules for doing random encounters are intended to compress game-time somewhat during periods when random encounters aren't expected to be very likely, while also taking into account PC skills and actions. To summarize, random encounter checks are made against a basic DC of 10 (baseline 50%) at a pre-set frequency. These rules aren't meant to hinder you from handwaving the PCs across miles of hostile terrain because you need them to get to the intended destination as soon as possible. These rules are for making random encounters simpler without making them too unrealistic.
Rule #1: All random encounter checks are made as a d20 roll (concealed roll by the DM). The DC of a normal random encounter is 10. If a 'hard' random encounter is desired (defined as APL+2 or higher), its DC is 19. If a 'special' random encounter is desired, its DC is 20 (defined as an encounter with anything that could be described as a "special guest star" -- a pre-generated NPC, a monster with class levels, an intelligent magic item, etc.)
Rule #2: The DM assigns an encounter frequency which would represent the amount of time a party would have to spend in an area before the odds rise to 50% of having a random encounter with a hostile creature. Here are some examples:
A rolling grassland with few trees being scoured by several troops of cavalry : 1 check per round
The urban jungle on the 'bad side' of town: 1 check per minute
A minor highway known for frequent attacks by brigands: 1 check per hour
Sailing an open-ocean trade route vulnerable to piracy: 1 check per day
Trailblazing a new path through an uninhabitable and environmentally hazardous wilderness: 1 check per week
The check frequency operates on a time scale as follows (you can skip this part for now.)
1 Round
5 Rounds
1 Minute
5 Minutes
10 Minutes
1 Hour
2 Hours
12 Hours
1 Day
1 Week
It is DM's discretion what is the 'baseline' for encounter check frequency for a given territory, as appropriate for a party of four or five mounted characters who are encamped (stationary) and don't advertise their presence by making a lot of noise or building a campfire, but don't go to extremes to conceal it either by using invisibility or digging themselves a foxhole and covering themselves with camouflaging.
Ultimately it probably doesn't matter whether a random encounter occurs between 8 and 9 o'clock in the evening. The important thing is whether the encounter is happening at all. We don't force clerics and wizards to decide whether their prayers and studies happen at 7:53 or 7:58, only that it happens (and preferably when nothing else is going on that's important). If the minute of the hour really is relevant, the DM can always roll a d60 (10 X (d6-1) + 1d10). And should we care if an interruption happens on the 3rd round of a particular minute or the 8th?
Rule #3: Various actions can increase or decrease the encounter check frequency. Traveling instead of remaining still, carousing and shouting, building a huge bonfire, wearing camouflaged clothing, casting an hours-long Silence spell, different things can influence this. Rather than stacking on tons of modifiers to the d20 roll based on individual PC behavior, we raise or lower the frequency by one or more steps on the scale above for the most significant factors. Thus, some PCs traveling on foot and singing loudly on a minor highway known for frequent attacks by brigands is much more likely to encounter brigands than the same number encamped overnight in a large copse away from the road, with strict noise and movement discipline aided by magical concealment.
Generally, a minor blunder (such as failing a Stealth check within 5 points) raises the frequency by one step, a major blunder (failure by 5 or more points) costs two steps, and catastrophic blunders (party in-fighting leading to verbal and physical fisticuffs) could jump the frequency up by 3 steps (and could easily guarantee drawing unwanted attention). Conversely, taking extra measures to effect cover or concealment via a series of Stealth checks, cloaks or rings of invisibility, etc., should lower the frequency by one or more steps.
Essentially, the encounter check frequency is just a "time compression" mechanism. As an example: There is normally a check only once per hour, meaning the PCs can count on peace and quiet for one hour at a time, but an argument arises that provokes the DM into reducing the frequency to 10 or even 5 minutes--the PCs will be making decisions about their behavior for 5 or 10 minutes at a time. If they are maintaining equipment or scribing scrolls or whatever, they'll probably just keep doing what they were doing as long as nothing unusual happens.
Rule #4: It's not the DM's responsibility to automatically warn the players that they are doing something to draw extra attention to themselves (and this may become obvious by itself in short order when a nasty predator comes to see what all the noise is about). You could put it on the PCs to realize this themselves with Intelligence or Wisdom checks, but this isn't absolutely necessary either.
Rule #5: You're not locked in to the above frequency chart for all circumstances. Feel free to customize the frequency chart according to taste and campaign setting and environment.
Rule #6: I use the following method of creating a table of random monsters.
(a) Make a list of monsters (along with book and page number if necessary) within a reasonable (and sporting) range of CR values. Avoid assigning random values for the number of monsters to be encountered (such as 1d8 Orcs); 1 Orc is considerably less of a challenge than 6 of them.
(b) OPTIONAL The last entry of every encounter table I make is a "Special", which is something of a "DM's Choice" but usually amounts to me picking out some rarely-used monster out of one of the Bestiaries or an unknown NPC borrowing stats from an existing NPC's sheet.
(c) Decide whether to use a d20, d100, or some other die size which will randomly choose the monster. This die size should be greater than the total number of entries on the table (preferably by 50% or more)
(d) Each entry should be assigned a number of 'tallies' (minimum 1) on the table. The total number of tallies should equal the die size or (especially in the case of percentile dice) each tally could represent 4%, 5%, or 10% of the total. The more common you want a random monster to be, the more tallies it should get. Lower-CR monsters should have more tallies than higher-CR ones. The "Special" entry usually never gets more tallies assigned to it than those regular entries with the fewest number.
(e) After assigning all the tallies, convert them into ranges. For instance, 5 tallies on a d20 table could equal a range of 7-11, and 5 tallies on a percentile table (1=5%) might equal a range of 26-30. Work out the range of values for every entry, making sure all possible values of the die roll are used with no overlap.
Once you've determined that a random encounter is to occur, roll on the encounter table to see what monster showed up.
-the end-
Part of the fun of any campaign that involves travel through dangerous territory is the chance of a random encounter. Of course it is not really a random encounter when you as the DM arbitrarily decides that the party has run into one or more random monsters (which for our purposes will include hostile NPCs with class levels, whether humanoid or not). There is no allowance for the players' influencing the likelihood of being ambushed. Rather, there should be a chance for both possibilities--the encounter happens, or it does not.
The easy method is for you to roll a basic d20 and pick some "encounter DC" that corresponds to your intuitive guess about the density of population of wandering monsters peculiar to that area of your game world. You could allow the PCs some skill checks to avoid detection, but there can be multiple encounters per day/night and more than one chance to be discovered while encamped--for any given patch of terrain, the natives will know the lay of the land better than any traveler and may well trace the PCs to their location via their scents or tracks. Therefore no location (notwithstanding magical protection such as a Rope Trick or Mansion) can be 100% secure. So there should always be a nonzero chance for a random encounter, unless you judge the pacing of the campaign plot should omit the delay of the occasional random encounter.
I also think it can become tedious choose and stick with a given frequency to test for random encounters--doing an encounter check for each hour between sunset to sunrise seems like a waste of die rolls especially if you are using a high DC for ruling the encounter check a 'success' (i.e., something shows up). Moreover, repeating this process over several days' travel can be a nuisance and slow down the dramatic pace of a journey between urban waypoints. On the other hand, if you go the other way and only roll for a random encounter _per day_ of travel, you eliminate the possibility of having multiple encounters per day as a result of PCs doing rather poorly at keeping out of sight and being quiet--so did ALL the PCs somehow succeed on all their Stealth and Survival checks?
These house rules for doing random encounters are intended to compress game-time somewhat during periods when random encounters aren't expected to be very likely, while also taking into account PC skills and actions. To summarize, random encounter checks are made against a basic DC of 10 (baseline 50%) at a pre-set frequency. These rules aren't meant to hinder you from handwaving the PCs across miles of hostile terrain because you need them to get to the intended destination as soon as possible. These rules are for making random encounters simpler without making them too unrealistic.
Rule #1: All random encounter checks are made as a d20 roll (concealed roll by the DM). The DC of a normal random encounter is 10. If a 'hard' random encounter is desired (defined as APL+2 or higher), its DC is 19. If a 'special' random encounter is desired, its DC is 20 (defined as an encounter with anything that could be described as a "special guest star" -- a pre-generated NPC, a monster with class levels, an intelligent magic item, etc.)
Rule #2: The DM assigns an encounter frequency which would represent the amount of time a party would have to spend in an area before the odds rise to 50% of having a random encounter with a hostile creature. Here are some examples:
A rolling grassland with few trees being scoured by several troops of cavalry : 1 check per round
The urban jungle on the 'bad side' of town: 1 check per minute
A minor highway known for frequent attacks by brigands: 1 check per hour
Sailing an open-ocean trade route vulnerable to piracy: 1 check per day
Trailblazing a new path through an uninhabitable and environmentally hazardous wilderness: 1 check per week
The check frequency operates on a time scale as follows (you can skip this part for now.)
1 Round
5 Rounds
1 Minute
5 Minutes
10 Minutes
1 Hour
2 Hours
12 Hours
1 Day
1 Week
It is DM's discretion what is the 'baseline' for encounter check frequency for a given territory, as appropriate for a party of four or five mounted characters who are encamped (stationary) and don't advertise their presence by making a lot of noise or building a campfire, but don't go to extremes to conceal it either by using invisibility or digging themselves a foxhole and covering themselves with camouflaging.
Ultimately it probably doesn't matter whether a random encounter occurs between 8 and 9 o'clock in the evening. The important thing is whether the encounter is happening at all. We don't force clerics and wizards to decide whether their prayers and studies happen at 7:53 or 7:58, only that it happens (and preferably when nothing else is going on that's important). If the minute of the hour really is relevant, the DM can always roll a d60 (10 X (d6-1) + 1d10). And should we care if an interruption happens on the 3rd round of a particular minute or the 8th?
Rule #3: Various actions can increase or decrease the encounter check frequency. Traveling instead of remaining still, carousing and shouting, building a huge bonfire, wearing camouflaged clothing, casting an hours-long Silence spell, different things can influence this. Rather than stacking on tons of modifiers to the d20 roll based on individual PC behavior, we raise or lower the frequency by one or more steps on the scale above for the most significant factors. Thus, some PCs traveling on foot and singing loudly on a minor highway known for frequent attacks by brigands is much more likely to encounter brigands than the same number encamped overnight in a large copse away from the road, with strict noise and movement discipline aided by magical concealment.
Generally, a minor blunder (such as failing a Stealth check within 5 points) raises the frequency by one step, a major blunder (failure by 5 or more points) costs two steps, and catastrophic blunders (party in-fighting leading to verbal and physical fisticuffs) could jump the frequency up by 3 steps (and could easily guarantee drawing unwanted attention). Conversely, taking extra measures to effect cover or concealment via a series of Stealth checks, cloaks or rings of invisibility, etc., should lower the frequency by one or more steps.
Essentially, the encounter check frequency is just a "time compression" mechanism. As an example: There is normally a check only once per hour, meaning the PCs can count on peace and quiet for one hour at a time, but an argument arises that provokes the DM into reducing the frequency to 10 or even 5 minutes--the PCs will be making decisions about their behavior for 5 or 10 minutes at a time. If they are maintaining equipment or scribing scrolls or whatever, they'll probably just keep doing what they were doing as long as nothing unusual happens.
Rule #4: It's not the DM's responsibility to automatically warn the players that they are doing something to draw extra attention to themselves (and this may become obvious by itself in short order when a nasty predator comes to see what all the noise is about). You could put it on the PCs to realize this themselves with Intelligence or Wisdom checks, but this isn't absolutely necessary either.
Rule #5: You're not locked in to the above frequency chart for all circumstances. Feel free to customize the frequency chart according to taste and campaign setting and environment.
Rule #6: I use the following method of creating a table of random monsters.
(a) Make a list of monsters (along with book and page number if necessary) within a reasonable (and sporting) range of CR values. Avoid assigning random values for the number of monsters to be encountered (such as 1d8 Orcs); 1 Orc is considerably less of a challenge than 6 of them.
(b) OPTIONAL The last entry of every encounter table I make is a "Special", which is something of a "DM's Choice" but usually amounts to me picking out some rarely-used monster out of one of the Bestiaries or an unknown NPC borrowing stats from an existing NPC's sheet.
(c) Decide whether to use a d20, d100, or some other die size which will randomly choose the monster. This die size should be greater than the total number of entries on the table (preferably by 50% or more)
(d) Each entry should be assigned a number of 'tallies' (minimum 1) on the table. The total number of tallies should equal the die size or (especially in the case of percentile dice) each tally could represent 4%, 5%, or 10% of the total. The more common you want a random monster to be, the more tallies it should get. Lower-CR monsters should have more tallies than higher-CR ones. The "Special" entry usually never gets more tallies assigned to it than those regular entries with the fewest number.
(e) After assigning all the tallies, convert them into ranges. For instance, 5 tallies on a d20 table could equal a range of 7-11, and 5 tallies on a percentile table (1=5%) might equal a range of 26-30. Work out the range of values for every entry, making sure all possible values of the die roll are used with no overlap.
Once you've determined that a random encounter is to occur, roll on the encounter table to see what monster showed up.
-the end-
