21st Century Philosopher: Call of Cthulhu 7th Ed

1921 Everest with Mallory Expedition

I thought Skill Checks were explained pretty well in the Keeper Rulebook. But of course people still have questions.

Here are the basics:

Roll your skill % or less on percentile dice and succeed. Roll above and fail. The lower the roll the better.

Crit > Extreme > Hard > Regular > Failure > Fumble > Crit Fumble (house rule)
Roll 01, Critical success.
Roll 1/5 your skill %, rounded down, Extreme success.
Roll 1/2 your skill %, rounded down, Hard success.
If success, but above 1/2 skill %, then Regular success.
If failure, but not a fumble, then failure.
If skill is 49% or less, roll 96-100 then fumble.
If skill % is 50% or higher, roll 100 then fumble. Also Critical fumble (house rule).

On failure, not fumble, you can Push to reroll OR Spend Luck (optional rule).

Push, use another skill or somehow try again. See p.84 Keeper Rulebook.

There must be time to do the Push whether seconds or hours. You cannot Push combat, Luck rolls, or SAN checks.
If success, no negative consequences.
If failure, consider it a Crit fumble. I generally discuss what the Crit fumble would be and offer the deal to the Player. If accepted, then the reroll is done, otherwise the previous die roll will stand.
Skill improvement check is earned if success.
Luck may NOT be spent on the reroll.

Spend Luck (optional rule), spend 1 Luck point per 1% decrease in die roll. See p.99 Keeper Rulebook.

You cannot spend Luck on SAN checks, Luck rolls, or damage rolls.
Criticals, fumbles, and firearm malfunctions cannot be modified by Luck points.
Skill improvement check is not earned if Luck points were used.
Luck can be spent in combat, but various GMs house rule that you cannot spend Luck in combat or cannot spend Luck in the last act of a scenario.

Difficulty Level. See p.83 Keeper Rulebook.

If the opponent's skill or characteristic is 90%+, an Extreme success is needed to beat or succeed in the task.
If the opponent's skill or characteristic is 50%+, a Hard success is needed.
Otherwise, a Regular success is needed.
Use this for most tests except for combat or a named NPC (if the GM desires).

Opposed Skill Rolls. See p.90 Keeper Rulebook.

Opposed Rolls should be used for combat or Player vs Player.
If it's Player vs NPC, then use the Difficulty Level based on the NPCs skill or characteristic.
Opposed Rolls cannot be pushed.
Compare the level of success (Crit, Extreme, Hard, Regular, Failure).

Better result wins.
Tie, compare skill %, higher wins. If still tie, impasse until next round or both reroll.
If both fail, then impasse until next round or reroll.

Bonus or Penalty dice. See p.91 Keeper Rulebook.

If conditions warrant it, allow a bonus or penalty die. Most times this is used in combat for point blank firearms, outnumbering an opponent, partial cover, maneuver on someone bigger than you, etc.
If a penalty die is used and the result is a success, a skill improvement check is earned.
If a bonus die is used and the first die roll is a success, a skill improvement check is earned. Note this is contrary to the rules where if a bonus die is used there is no skill improvement check, but in Pulp Cthulhu, some Pulp Talents skill always have a bonus die, so the PC will never advance that skill. So, as a workaround, if the non-bonus die roll is a success, a skill improvement check is earned. Therefore, if you roll multiple dice at the same time, make sure that the non-bonus die is distinguishable from the bonus dice.
Bonus/Penalty dice are single ten's dice (00, 10, 20, etc). But Roll20 rolls a complete new set of % dice which is not exactly according to the rules. Overall, it's close enough and we use the die roller for Roll20 as-is without reinterpreting the die rolls.
How to read the purple die roll on Roll20 character sheet, Accounting skill is at 60%:
For a push or reroll, reroll all bonus and penalty dice.

Cooperating. See Physical Human Limits, p.88 Keeper Rulebook. An example of this is lifting a huge weight off of another PC.

Subtract skill or characteristic of weaker PCs from difficulty level.
PC with highest skill rolls vs difficulty level. See Difficulty Level above.
If the die roll is a failure, all the PCs who cooperated will fail as a group.
First Aid is a special case, max two PCs may try to do it together, both make die rolls. If any one succeeds, then the first aid is successful and apply the first aid once. Any subsequent tries are Pushed rolls which will result in more damage including possibly amputation or death on failure. See p.65 Keeper Rulebook, First Aid.

Combined Tests. See p.92 Keeper Rulebook. An example of this is requiring two skills such as Physics and Elec Repair in order to succeed (to fix an Atom bomb). Instead of rolling twice, once for each skill, roll once and if the die roll is below both skill %, then it's a success. The reason for this is that if you require multiple rolls, the chances of success are vastly decreased and unfair.
Group Stealth. See my blog post on Group Stealth.

Q (PB): I have a group climbing Mount Everest and they need to set up ropes beforehand which I'm going to let them use their Climb skill.

Is there a rule for cooperating on skills?

A (MH): See Cooperating, above. Subtract the lowest skill scores from the difficulty level and have the PC with the highest score roll for success. e.g. climbing a difficult area might require 150% difficulty level. So, subtract all the lower skill climbers. Say the 2 people helping are a total of 80%, so the difficulty becomes 70%. See Difficulty Level above. 50%+ difficulty requires a Hard success. So, the PC with the highest score let's say 90% climb can only succeed with a 45%, otherwise all 3 PCs fail. It doesn't mean they fall off the mountain (fumble), but they can't make it up this section of the mountain and must try a different route.

If they do fumble, a 100 roll for this case, then I'd rule they all peel off the mountain and each need to do an emergency arrest. They'll take SAN loss and some HP damage. The number of failures will determine the damage and setback on the climb. 1/2 HP loss = Major Wound where someone broke a limb or rib.

Q (JBB): Has anyone ever done a size roll? What constitutes a SIZ roll?

A (MH): "To see over a wall, to squeeze through a small opening, or even to judge whose head might be sticking up out of the grass, use size." See p.31 Keeper Rulebook, SIZ.

For squeezing through a small opening, reverse the die roll, you must fail your SIZ to squeeze through the opening. The bigger your SIZ, the harder it would be to get through a small opening. Depending on the size of the hole, you may say squeezing through the hole causes scraping damage based on how well they succeed. This also assumes the PC is pushing their equipment ahead of them or dragging it from behind.

For instance, spelunking in a cave and trying to get through a narrow passage:

Fail = squeezed through, no side-effects.
Regular Success = minor scrapes, but squeezed through, 1 pt damage.
Hard Success = failed to squeeze through and major cuts cause 1d3 damage before you gave up.
Extreme Success = stuck and wedged in, take another round to get out and take 1d6 damage.
Critical Success = stuck and need help to get out and take 6 pts (max damage).

For looking over a wall, it may not require a die roll. For instance, the GM can rule that if you are SIZ 80+, you can automatically see over the wall; otherwise a Climb, Jump, or something similar is required to do so.

Q: Is it true that you gain SAN for attaining 90% or more in a skill ability?

A: Yes, but only during the investigator development phase. If you create an investigator already with a skill at 90% or more, you will not gain this SAN bonus.

Add 2d6 SAN for mastering a skill at 90%+. This represents an increase in self-esteem. See p.94 Keeper Rulebook, Skills of 90% or More.

Q (JN): My Investigators are too weak in key skills needed to forward the story or have a chance at improving that skill. They're realizing it's important to know how to drive a car so they can go the gun range or spend time in the library. Should I house rule ways to increase their skills?

A: There are many ways to address this. First, there's some misconception here. Skills should only be rolled when failure is important to the story. So, even though PCs didn't put points in Drive, they have the Drive skill at default, which means they can normally drive a car. They only need to roll when in a car chase or when trying to run someone over. Same for Own Language skill, you don't need to roll when speaking with someone. You only need to roll when trying to decipher some old text.

For inexperienced Players, I allow new PCs, after their very first session, to move skill points around from skills they've never used. This rarely happens as I do explain to new Players what skills are normally used.

As a GM, you can also allow failed rolls to succeed at a cost. Especially for key clues. See p.194 Keeper Rulebook, Rolling Dice, Dice Rule 3: Losing a roll doesn't necessarily mean failing a goal.

For between sessions, there is training. See p.98 Keeper Rulebook, Training. So, no house rule is needed.

Q: If a Player switches skills after a failure is it a Pushed roll? For example a PC tries Charm and then switches to Persuade?

A: If the goal is still the same, such as gaining info or a clue, any switch in tactics or rerolls are Pushed rolls.

For social skills: Intimidate, Charm, Persuade, Fast Talk. Any switch in tactics or rerolls are Pushed rolls, even by a different PC. This prevents Players from doing the following: PC 1 tries Charm, failed. PC 2 tries Fast Talk, failed. PC 3 tries Persuade, failed. PC 4 tries Intimidate, failed. Then PC with highest social skill tries a Pushed roll. Yeah, this is an extreme example, but I think you get why this shouldn't be allowed.

I consider any re-try even with a different social skill a Pushed roll because it's really fishy if someone tried to Charm you to get past the door, then moments later, either the same person or their friend tries to Fast Talk through the door. I tell the players that if you do that, that's a Push and if you fail, the doorman gets pissed off and decides to teach you a lesson. e.g. it'll be a combat situation. Of course, if they beat him down, they'll get past him.

As an aside, if you fail a Locksmith (lock pick) and then kick the door in, the STR test for kicking in the door is NOT a Pushed roll as the consequence is that it's noisy and obvious someone broke in. And the original point of trying Locksmith was to quietly and unobtrusively get through the door.

Q: I have a Pulp Talent that automatically gives me a bonus die. "No tick is earned if the roll used a bonus die." See p.94 Keeper Rulebook, Rewards of Experience: The Investigator Development Phase. Does that mean I'll never improve that skill?

A: Yeah, that doesn't seem fair. So, I recommend using different colored dice for the bonus die or dice. And if the original skill roll would have succeeded (without the bonus dice), then that skill earns a tick mark. Furthermore, if penalty dice are used, you must pass the skill check using the penalty dice to get a check mark.

Q: PCs are using Library Use and they fail their rolls. What should I do?

A: If it is a core clue, give them the clue anyway, but rule that this took all their time and they can't research anything else that day. They have to come back the next day to research something else.

If the clue isn't really important, then you can just tell them they find nothing. PCs can also push the Library Use by staying past the closing time, stealing books, breaking into the restricted stacks, etc. Some pushed failures may lead to arrest, being banned from the library, or discovering that the needed pages are indeed missing.

Q: During the Investigator Development Phase, can you increase your skill over 100%?

A: Yes. If you roll above your current skill or roll 96+, increase that skill by 1d10. See p.94 Keeper Rulebook, Rewards of Experience: The Investigator Development Phase, second column.

Also having your skill over 100% doesn't mean you are infallible. It does mean you can still fumble by rolling 100 and during an opposed roll, you can still roll a worse success than your opponent.

Q (MW): What's the difference between Acting and Disguise? They seem interchangeable.

A: I would think this matters more based on the PC's profession. A stage actor would have Acting skill. A spy would have Disguise skill. A stage actor might be really good at delivering Shakespeare lines or pretending to be a Star Ship Captain, and in a pinch pretend to be a homeless bum staking out a suspect. A spy would be able to look like a homeless bum during a stake out, change to a respectable businessman in a suit, turn into a woman/man on a short notice, but won't be able to dazzle a crowd with a rousing speech.

Q: If I don't have Cthulhu Mythos can I roll Occult instead? And if that works, why do I need Cthulhu Mythos?

A: Here's the Q&A for Occult vs Cthulhu Mythos skill. If TLDR, it's up to the GM. Generally, no. But if the GM is being nice, maybe an extreme Occult success might give a hint of the truth.

Q (JV): When a scenario says something along the lines of "A successful Psychology roll during their meeting reveals that Hattie is hiding something from the investigator." is the keeper supposed to tell the investigator to make a Psychology roll or is it only for if the investigator specifically says they want to make a psychology roll?

A (MH): I treat some skills as Passive (always happening), so the PCs always get to roll dice. Those skills are: Psychology, Listen, and Spot Hidden (you see something odd vs tossing the place which would be an Active Spot Hidden). If there's some sort of clue or danger, I'd say, "Those in the room roll xyz." Sometimes it's a clue, sometimes it's someone sneaking up on them as a precursor to an attack.

But I don't use Psychology as a 100% lie detector (unless they get a Crit or Extreme success), otherwise you can say, "Hattie seems nervous, she doesn't seem entirely truthful or she's worried about something." Then the PCs need to do a follow up with a social skill.

Q (JV): Many of the scenarios start out needing to gather clues from various establishments: libraries, city hall, courthouse, Miskatonic U library, local newspaper archives, historical society, social/business clubs, etc.

How do you have it so the beginning of every scenario doesn't devolve into the investigators going to 20 or 40 different (but somewhat similar) locations to track down clues?

But also it feels like it would be pointless if you always just give all the clues to the investigators at the first place they stop. Plus some of the clues just wouldn't make any sense as to why you'd find them at a certain place.

How do you balance these extremes?

A (MH): For Library Use, I let every PC do research, but I ask what the topic is. If they roll well, I may give them an unrelated clue (to that topic) they just happen to run across. This takes time. A failed roll means that they spent all day looking up stuff and didn't find anything (or just the core clue). They'll have to return the next day to do more research (or go to a different establishment).

Reduce the number of research locations or just assume the PCs split up and go to different locations based on the topic they choose. If they're looking up birth records, they have to go to City Hall. Newspapers in the library archives or a newspaper's archives. Deed or property info, City Hall. Membership records, the specific club. Just assume the PCs know which location to go to and just have them roll Library Use based on the topic they're looking up. Don't bother with asking them where they're going to.

Generally getting all the clues isn't an issue. Even with all the clues, they'll have to figure what's really going on, unless your clues spells everything out (hopefully not). If the scenario is designed properly, the clues they find would only be for Act 1, when they're in Act 1. Act 2 clues won't be unlocked until they understand what else to research or go to a different location (Act 2).

Now, if you want to make Library Use more exciting, you can do the following, but sparingly:
Library Use or That was Boring.

Q (TJ): If you increase your EDU with an Improvement Check, from 80 to 88 for instance, does your "Language Own" skill increase accordingly?

A (MH): EDU can't increase. There is no Improvement check for characteristics after character generation. If you are talking about during character generation, then you increase your Characteristics before you set your defaults in skills and add skill pts. So, yes, your default Language Own increases to EDU during character generation.

Q: What if your PC ages up to the next age group during a game?

A (MH): I assume if it's unnatural aging, you get the physical penalties (or growth), but not any mental increases. If the game skips years (e.g. 10 years between chapters of a campaign), then I'd say allow the EDU improvement from life experience. If the PC is going through numerous scenarios, then I'd skip the aging part as the scenarios does the wear and tear on the physical and mental reserves of the PC. And check marks from scenarios is how the PC grows in skills. Also between scenarios, if this is an ongoing campaign, PCs can take classes, hobbies, etc which will add skill pts which will in effect be an EDU increase (life of hard knocks and formal training whether from school or work), though it won't be reflected in the EDU score. In my experience this never comes into play as most PCs die within a year or two especially in a long campaign. Either they'll die or they'll make it to the end and that's the end of the series and the PC is retired.

Q (P): I am a life long nerd who has studied math, physics, and chemistry at the college level. I play an uneducated character. When we get evidence while mystery solving, all players are spitballing ideas around the table trying to figure it out and where to go next. We got some chemical evidence recently which involves rather basic stuff, even for 1920s standards, and I know what they are but my street-smart character didn't have school or even public TV programs. I doubt he knows an acid cancels a base, even if he's had alka seltzer for a hangover; he doesn't know what it is doing.

How do you handle this type of thing when it happens to you? I want to suggest things based on my real knowledge because I want to solve the case. Do you offer your real world suggestion to the Professor character in your party and pretend he came up with it? Do you keep mum and maybe miss out on this big clue? Do you whisper to the GM that the scientist should make a knowledge roll?

I like role playing but when your real life specific knowledge set comes up, how do you "suppress" it? I could see this applying to any specific study: literature, military tactics, culinary, history, etc.

A (MH): The issue is if you decide to roll Chemistry skill, the base chance of success is 1%. So, even saying, I have an idea, but can I roll to see if my PC thinks of it is a non-starter.

You can play ignorant, but if you can come up with some in-period example that your character can reasonably come up with that would work, I'd do it. e.g. your hobo character says, "I remember one time when Gus got this battery acid all over him and Jimmy, who's real smart, dumped a box of baking soda on him, and that stopped the burning. Don't know how that works, but do you think this is somehow related?"

This is a legit way of roleplaying. You stay in character and help resolve the mystery.

Q (S): As a GM, how do you decide whether to add a Penalty die or make it a Hard difficulty roll?

A (MH): Set the Difficulty Level first, depending on the difficulty of the obstacle (see below). Then every adjustment after that would be bonus/penalty dice.

For example, lockpicking a lock. Is it just a normal door lock? A wall safe? A bank vault? The type determines the Difficulty level.

p.82 Keeper Rulebook, Determining the Difficulty Level tells you a task is only Hard if it challenges a professional. Extreme only if it challenges an expert or is on the edge of humanly possible. So, this doesn't change. The Difficulty Level is set when the obstacle is created. Such as a hardened lock (Hard), a bank vault door (Extreme), a NPC that is Hard to convince (p.83 Keeper Rulebook, based on the opponent's skill).

p.112 Keeper Rulebook, Firearms. The Difficulty Level is set based on Range. Then p.113 Keeper Rulebook, All Firearm Adjustment Modifiers (Aiming, Multiple shots, Point-Blank, etc.) are bonus and penalty dice. Once the Difficulty Level is set (based on range and it normally is Regular difficulty), penalty/bonus dice are added afterwards based on situational modifiers. The only special rule is p.116 Automatic Fire, "If this would incur 3 penalty dice, stick with 2 and raise the difficulty level by one step." So there's a max of 2 penalty dice, once that is reached, raise the difficulty level instead. It is interesting that Point-Blank (which is a Range) adds a bonus die, but I assume that's because there's no Easy difficulty level.

Q (GG): How do PCs increase their characteristics? If the answer is "they can't," I will find that very unsatisfying-- after all, in real life, anyone can increase their strength substantially just by going to the gym every day for a few months!

A (MH): Characteristics (stats) don't mean much in CoC, they're mainly there for their initial occupation skill % allocations. The only time it's consistently used is the Build Damage Bonus (DB) for Fighting (Brawl). Even if you increase DEX, your dodge won't go up, it'll be easier to train in the Dodge skill instead. So, you could spend time doing body building and if you increase the right stats, your Build might go up. We only use the stats in the game if the PC didn't have a specific skill, then we might say, roll DEX or (half DEX) to see if you succeed. The only time stats are used are mainly for saving throws, such as CON or (half CON), or STR for lifting something big. In my campaigns, I do let PCs train in skills and get a "check mark" for improvements.

I would let you do STR training, but the gain would be the same process. STR training requires continuous upkeep. Look at Arnie, he's shrunk even though he still trains, but not as hard, so even if you increase your STR, it will decrease over time unless you do upkeep.

For normal training, I'd go with p.98 Keeper Rulebook, Training. Notice most training requires 4 months of dedicated training.

For long cruises or travel, PCs want to read books or train in skeet shooting or a foreign language. Most of the time, I require a POW check to see if they have the will power to continue training while seduced by free food and entertainment. If they succeed, then they get a check mark on that skill for improvement.

In my Miskatonic University campaign, I did the following, since students started with low EDU and less occupation skill % allocations:

Figure out your semester's classes. 3 semesters a year (Fall, Spring, Summer).
A full class schedule for Fall and Spring includes:

4 Classes.
1 Varsity Sport or Other Activity.
1 Optional Additional Activity.

After completing a class each semester:

Skill Gain: Roll 1d10, add this to a skill related to your course work as long as that skill is below 70% for undergraduates, 90% for graduate work.

For more details go here: https://sites.google.com/view/miskatonic-university/home/classes

Q (GDH): Credit Rating (CR), Spending Level, Cash, Assets. Do you use CR to buy things? Luck to see if it's available? EDU or INT to see where to buy something?

A (MH): p.46 Keeper Rulebook, Cash and Assets explains pretty clearly what they are and how they are used. p.61 Keeper Rulebook, Credit Rating explains what CR is. p.95 Keeper Rulebook, Credit Rating and Investigator Expenditure explains more about CR and its use.

TL;DR. CR is used to influence someone such as getting invited to a social event or using your social status to impress someone. It's not a skill to roll against to buy something. Most people know where to go buy something, so there's no roll for that unless you're looking for something unusual or illegal. For those cases, I might make them roleplay that. I look at their Spending Level for what's normally available such as buying a meal or renting a room; this only becomes an issue if the PC is poor. Most PCs can afford normal items and know where to purchase things. But when they say, I want to hire an armored car, hire 20 thugs, buy a case of dynamite, then I look at Spending Level and Cash. Worse case is they sell some Assets which may affect their CR, but that takes time. Also if they're out in nowhere, they'll have to depend on their cash on hand, maybe there's no Western Union out there to wire a bank to give them money. Most people won't take a personal check from a stranger.

If the item they want is very unlikely, then I'd just say it's not available. If it might be available such as dynamite in a mom and pop rural grocery store (for clearing stumps or dynamite fishing), then I might ask for a Luck roll. If they're looking for a Tommy gun, the answer is no. A shovel, yes.

Q (DV): Question regarding strength or power checks vs an inanimate object like a door or a ward.

If a doorway is empowered by a ward that is supposed to stop demons from entering through it and has a POW of 80 and requires a Hard power roll to bypass. How does the demon roll to get past this ward. For fun let’s say the demon has a power of 100.

A (AM): Demon rolls a Hard POW roll, so in this case hard would be 50%.

Q (DV): But then why does the POW of the ward matter?

A (MH): They pre-calculated it for you, see p.83 Keeper Rulebook. If door had POW 90+, you'd need an Extreme success; POW 50+, Hard success; POW 49 or less, Regular success.

They gave you the POW in case multiple things are working together to break through the door. See p.88 Keeper Rulebook, Physical Human Limits on how cooperating entities can work together and break through a door. If multiple entities were trying to break through, subtract the weakest entity's POW from door's POW. Then figure out if strongest demon still needs a Hard success or a Regular success.

Other Q&A:

CoC 7th Combat Q&A

CoC 7th Insanity Q&A

CoC 7th Magic Q&A

Discussion of Luck Spends and some Q&A