D&D 5E How to Handle Monster Knowledge Checks

[iserith]

Basic Rules, page 61:
"An Intelligence check comes into play when you need to draw on logic, education, memory, or deductive reasoning. The Arcana, History, Investigation, Nature, and Religion skills reflect aptitude in certain kinds of Intelligence checks."

Basic Rules, page 58:
"The DM calls for an ability check when a character or monster attempts an action (other than an attack) that has a chance of failure. When the outcome is uncertain, the dice determine the results."

"If the total equals or exceeds the DC, the ability check is a success—the creature overcomes the challenge at hand. Otherwise, it’s a failure, which means the character or monster makes no progress toward the objective or makes progress combined with a setback determined by the DM."

Therefore, if a player wants to know something about a monster, he must tell the DM that his character is taking a fictional action to draw on logic, education, memory, or deductive reasoning to learn or recall something about a particular monster. Then the DM must decide if the outcome of that fictional action is certain or uncertain. If it is certain - say, because it's a common monster or the character's background and experiences would reasonably make them knowledgeable about it - then the DM can just give them the information. If it is uncertain - say, because the monster is rare or obscure or the character's background and experience would not reasonably give them knowledge about it - then the DM asks the player to make an appropriate ability check, usually Intelligence. Almost any Intelligence-based skill can apply depending on the nature of the monster and the approach the player has stated for his character. For example, the acolyte cleric might try to recall something in his or her religious texts that referred to the monster (Religion). Or an observant rogue might watch how the monster does its thing, deducing from its behavior what its strengths and weaknesses are (Investigation).

The DC of the check varies, depending on the character's approach and the rarity of the monster and obscurity of information about it. If you only ever use 10, 15, or 20, however, it'll work fine. But what does success and failure on an ability check mean? The most common binary stakes are you either know (success) or don't know (fail). I, however, find that terribly boring and prefer to offer something on failure and sometimes a setback. So here's an easy go-to:

• Success: The character identifies the monster, its type, and some lore about it that can be used to deduce its motivations, strengths, and weaknesses. If the player beats the DC by 5, the character also knows the monster's resistances and vulnerabilities and abilities.
• Failure: The character identifies the monster and some lore about it that can be used to deduce its motivations, strengths, or weaknesses.
• Alternative Failure: As per Success, but the character's sudden revelation leaves him or her frightened until the end of his or her next turn. (Use this basic alternative failure condition as a model for variations on this theme.)

As with all stakes, I recommend making them transparent before the roll so the player knows what he or she is getting into when making that check. Some reasonable negotiation is acceptable.

Finally, if a player knows information about the monster, they can just say their character knows it and justify that knowledge in any reasonable way they like. However, since there is no guarantee that the DM hasn't changed the monster's stat block, it's smart play to confirm one's assumptions with in-game actions.

How do you handle them?

 

[Jester David]

Monster knowledge checks were always a bit of a metagame. They were a way to justify the character knowing or not knowing what the player knew, mostly the former so the PC could bypass defences and resistances. It always got a little funky when the PCs knew lots about obscure monsters and their weaknesses.
And it was always awkward as a DM, deciding what information to give out. To say nothing of the twist monsters where you don't want the PCs to identify it with a skill beforehand.

I'm always tempted to throw out lore like "if you throw down poppyseeds, they have to stop and count them all" or "they can't cross the shadow cast by a cat" or "they see movement and you become invisible when you stand still" and other folklore people would spread regarding monsters.

 

[Sunseeker]

Monster knowledge checks were always a bit of a metagame. They were a way to justify the character knowing or not knowing what the player knew, mostly the former so the PC could bypass defences and resistances. It always got a little funky when the PCs knew lots about obscure monsters and their weaknesses.
And it was always awkward as a DM, deciding what information to give out. To say nothing of the twist monsters where you don't want the PCs to identify it with a skill beforehand.

I'm always tempted to throw out lore like "if you throw down poppyseeds, they have to stop and count them all" or "they can't cross the shadow cast by a cat" or "they see movement and you become invisible when you stand still" and other folklore people would spread regarding monsters.

You're pretty spot on with this, knowledge checks were just a way to separate player knowledge from character knowledge.

When I set my knowledge checks for monsters, you will always get something, but the information is significantly more useful the higher you roll. Folklore is great when knowledge rolls are very low in place of saying "you learn nothing at all."

 

[ExploderWizard]

I kind of just assume that the creatures in the MM (if they are in the campaign world at all) are fairly well known and so is the folklore surrounding them. For truly ?? moments from the players there are always new monsters. I like the idea that not every monster possibly encountered is an actual species with an ecology, and so forth. In a world of magical experiments gone wrong with owlbears and such there really isn't a need for every possible monster to come from some place logically.

 

[Jester David]

You're pretty spot on with this, knowledge checks were just a way to separate player knowledge from character knowledge.

When I set my knowledge checks for monsters, you will always get something, but the information is significantly more useful the higher you roll. Folklore is great when knowledge rolls are very low in place of saying "you learn nothing at all."

It seemed to me that knowledge checks were a way with dealing with players who read the MM, by asking that they make a check to know common weaknesses like trolls being immune to fire. It always broke down a little when players could learn the name and weakness for really obscure monsters.

It's tricky with 5e as there's a range of 1/8 to 25 in CR but 1 to 11 for lore check mods. Would a level 1 scholar really be able to know the secret weakness of a CR 19 monstrosity (or the tarrasque). Off the top of their head.

This might work best requiring downtime days and lengthy research.

 

[iserith]

I don't see the checks as justification for a character knowing a thing or not - a player is free to say what his or her character knows to the extent he or she is in control of how the character thinks and acts. I would not ask for a monster knowledge check to test whether a character should be able to attack a troll with fire, for example. There is no uncertainty as to whether a character will attack a troll with fire after such an action has been declared (though there may be uncertainty as to whether that attack hits). I think it would be overstepping the bounds of the DM's role to say, in effect, "Nuh-uh, you metagamer, roll to see if your character even knows to do that."

In the end, I think the fictional action to recall or deduce information about monsters and the resulting check (or not, as the case may be) is a good way to verify one's assumptions about monsters or to discover something about monsters one hasn't encountered as a player (emphasis on player, not character).

 

[Greg K]

One of my 5e disappointments is that Dragon Lore and Fey Lore did not make it from one of the playtest documents.

In 3e, I added Demon/Devil Lore, Dragon Lore, Fey Lore, Spirit Lore (Elementals, ghosts, totem spirits, familiars), and Undead Lore (ghosts and corporeal undead). I also renamed Knowledge (Local) to Culture Lore (specific culture) which could apply to one of the human cultures, a non-human PC race, or another humanoid race (including giants) which acted as a more limited version of several skills including knowledge of local monsters.

If and when I run 5e, I will add the same skills. Everyone will get proficiency and/or advantage in the lore of their culture (there may be secret lore or less common knowledge not known by everyone). The monster skills will be available to certain classes or backgrounds as campaign appropriate or can be picked up after first level through training/downtime or as rewards

 

[nomotog]

I tend to require that the player ask something directly in order to make a knowledge check. Like is it immune to fire, or what dose it eat. No fishing expositions where the player makes a knowledge roll and I have to spout some random trivia. I tended to rule that a failure meant you couldn't ask any more questions, but I like your idea of the knowledge braking the player with fear. I never give my players incorrect information in a roll because that always ends up confusing them.

I am thinking about giving knowledge checks more power unlocking new actions almost to the level of spells. Like if you make a knowledge check on a monster, you might be told about how you can bribe them with the right kind of food, or how their ankles are a weak point to attack.

 

[nomotog]

It seemed to me that knowledge checks were a way with dealing with players who read the MM, by asking that they make a check to know common weaknesses like trolls being immune to fire. It always broke down a little when players could learn the name and weakness for really obscure monsters.

It's tricky with 5e as there's a range of 1/8 to 25 in CR but 1 to 11 for lore check mods. Would a level 1 scholar really be able to know the secret weakness of a CR 19 monstrosity (or the tarrasque). Off the top of their head.

This might work best requiring downtime days and lengthy research.

It could happen I they might have read about it in a book somewhere not knowing actually what it was till they saw it. It also could be that they know nothing about the actual creature but they make a guess based on what they do know. Like you know fire causes wounds that don't heal, so it might stop that troll from growing back their arm.

 

[Chocolategravy]

It seemed to me that knowledge checks were a way with dealing with players who read the MM, by asking that they make a check to know common weaknesses like trolls being immune to fire. It always broke down a little when players could learn the name and weakness for really obscure monsters.

It's tricky with 5e as there's a range of 1/8 to 25 in CR but 1 to 11 for lore check mods. Would a level 1 scholar really be able to know the secret weakness of a CR 19 monstrosity (or the tarrasque). Off the top of their head.

This might work best requiring downtime days and lengthy research.

If a player knows about a fictional monster for a game, it would seem reasonable that a character would know about the actual monster that actually eats people and as an adventurer is their job to know about. When the bards come to the inn to entertain, stories of dragons would be like Star Wars and gnolls and hobgoblins like episodes of Breaking Bad. It would be hard to believe that even the average person wouldn't have a huge amount of general monster knowledge.