Does D&D 5e have a rule for character knowledge about monsters?

Question

In the 3rd and 4th editions of D&D, there were explicit rules for determining if a character knew anything about a monster before them. In 3rd edition, for example, use of the Knowledge skill with a general DC of 10 + the monster's HD allowed for determining one fact, plus one fact per 5 points over the check.

Looking at the Intelligence section of the 5e PHB, I don't see any similar notation. Does 5e provide any guidance as to when a player could use their out-of-game knowledge about a monster, or when the player might be told things their character would probably know in-game?

Answer 1

Though it is not as clear as in previous editions, I believe that you would use the various intelligence skills based on what creature you are trying to learn about.

PHB, page 177 - 178, Intelligence Checks

Your Intelligence (Arcana) check measures your ability to recall lore about ... the inhabitants of planes

Your Intelligence (Nature) check measures your ability to recall lore about .. plants and animals

Your Intelligence (Religion) check measures your ability to recall lore about ... practices of secret cults

I take this as using the specific skills to figure out the in game knowledge. So, for example, I would organize it loosely in the following way:

• Arcana - Use this skill to discover more about elemental creatures, creatures of pure magic, arcane creations, and creatures of other planes

• History - Use this skill to learn more about creatures that play prominent roles throughout history. For example, goblins, kobolds, and most other humanoid races play significant roles in history.

• Nature - Use this skill to learn more about creatures tied directly to nature. Most often, this means animals (wolves, bats, etc.) but it could also be tied to druidic creations, or guardians of nature.

• Religion - Use this skill to learn more about creatures of religious creation. Servants of deities, undead, and other holy or unholy beings would be described with this skill.

In terms of setting the DC, use your best judgement based on the typical DC table found on page 174 of the PHB. For example, if you are in a town ravaged by kobolds consistently, it would be fairly easy for someone to know the few different roles they have in battle, so I'd give that a DC of 10.

Whereas if someone wants to know more about unholy creations most people don't see, but are commonly known about, that would be a religion check of 15 for medium difficulty.

Answer 2

You can actually buy Volo's Guide to Monsters in-game. From Tomb of Annihilation, page 25:

If the characters buy a copy of "Volos Guide to Monsters" (50 gp for a durable hardcover edition), they can put it to use. Any time they want to know lore about a particular monster described in the book, give them useful tidbits from Volo's Guide to Monsters. Do not impart game statistics, since such information would not be available in-world.

Answer 3

No such specific check exists - Play it by ear/DM ruling

You are correct that there is no comparable skill to be found in the PHB, likewise in the DMG or monster manual there are no references to skills specifically applicable to identifying a monster.

This is because the 5e skill system is designed to be a lot more fluid than previous editions. When trying to determine what skills that might indicate a character knows something about a particular creature there is no one clear answer for all situations.

Intelligence skills (pages 177-178 PHB) would indicate pre-existing knowledge of a creature:

• Acrcana might tell you about undead (knowledge of necromantic magic) but so might Religion (knowledge of a god of death). The exact skill would depend on the origin of the monster in question.

Further non-intelligence skills may be applicable as they denote experience and aptitude in a particular field. For example an interpretation of a few wisdom checks from PHB page 178

• If the undead were the result of a plague a Medicine check might provide information on them, while for a character who has previously encountered these undead a good Survival check may indicate experience tracking them and learning their behavior.

Ultimately what skill might provide information on what monster is entirely context dependent. Unless the monster manual entry in question says differently (specific beats general) use your own intuition or your players' interpretation based on the exact nature of the monster.

This attitude of applying skill checks based on common sense or group agreement is made more explicit on DMG page 239

Often players ask whether they can apply a skill proficiency to an ability check. If a player can provide a good justification why a character's training and aptitude should apply to the check, go ahead and allow it, rewarding the player's creative thinking.

It's a fuzzy area but so long as you aren't using Acrobatics checks to identify flumphs things should be fine.

Answer 4

While the OP asks for a presumably RAW solution according to 5e rule-sets, I have found the following 3.5e-derived home-brewed chart very helpful for this - I hope that it helps someone.

A Non-RAW Chart

NOTE: The approach I present below is:

1. loosely based on 3.5e.
2. home-brewed for 5e in a way that is completely consistent with the guidance given by the 5e PHB, page 177 - 178, Intelligence Checks (but goes further to create guidelines I use that are not RAW, but rather extend RAW).

I created the following chart for determining the skill required for characters to obtain in-game knowledge about a particular type of monster. This gives me a default type of check that can be done based on creature type. If the particular creature lends itself to be knowable via other skills, that's fine, but when I can't decide quickly, I use this chart:

\begin{array}{l|l} \textbf{Creature} & \textbf{Knowledge Check Type} \\ \hline \text{Aberration} & \text{Arcana} \\ \text{Beast} & \text{Nature} \\ \text{Celestial} & \text{Arcana} \\ \text{Construct} & \text{Arcana} \\ \text{Dragon} & \text{Arcana} \\ \text{Elemental} & \text{Arcana} \\ \text{Fey} & \text{Nature} \\ \text{Fiend} & \text{Arcana} \\ \text{Giant} & \text{Nature} \\ \text{Humanoid} & \text{History} \\ \text{Monstrosity} & \text{Arcana} \\ \text{Ooze} & \text{Nature} \\ \text{Plant} & \text{Nature} \\ \text{Undead} & \text{Religion} \\ \text{Legendary creatures}& \text{own type or History} \end{array}

Answer 5

Battle Master level seven feature, Know Your Enemy.

Starting at 7th level, if you spend at least 1 minute observing or interacting with another creature outside combat, you can learn certain information about its capabilities compared to your own. The DM tells you if the creature is your equal, superior, or inferior in regard to two of the following characteristics of your choice:

• Strength score
• Dexterity score
• Constitution score
• Armor Class
• Current hit points
• Total class levels (if any)
• Fighter class levels (if any)

That said, I play with open HP and, especially, open AC. I usually am not shy about giving the players the information in that feature, depending on the circumstances. I know it steps on the Battle Master's toe a little bit but that's how my group does it.