Investigation in 5e: How To Use It vs. Perception

Investigation is arguably the most useful Intelligence-based skill a character can have. Unlike Arcana, Religion, or History, it can be used in any situation you find yourself in. 

What Is Investigation in DnD 5e?

Investigation represents your character’s ability to pay close attention to detail when searching a location, researching a topic, or analyzing a circumstance. 

From Chapter 7 of The Player’s Handbook: 

When you look around for clues and make deductions based on those clues, you make an Intelligence (Investigation) check.

You might deduce the location of a hidden object, discern from the appearance of a wound what kind of weapon dealt it, or determine the weakest point in a tunnel that could cause it to collapse.

Poring through ancient scrolls in search of a hidden fragment of knowledge might also call for an Intelligence (Investigation) check. 

Who Should Use Investigation?

Everyone. However, there are some character types that will use it more than others, and it is important to know if you are playing in a campaign where this kind of specialization is important.

Below are different types of characters who would benefit from a high Investigation. 

The Researcher

Librarians, scientists, cloistered wizards, etc.; these characters are always fun to play, especially in high-action games where they could comedically be out of their element.

However, they will still need their time to shine, so if you are the DM in such a game, don’t give information away too easily. 

Typically, Researchers will do more than just search the room after a baddie is brought low.

They will want to take the clues they learn and go to a library, museum, or even a constabulary to search an evidence locker to see if they can find a pattern and identify who the real antagonist is and what their goals are. 

Often, a Researcher will have proficiency in Arcana, History, Nature, or Religion as well. Allow them to make these checks to guide their research. We have a house rule here at the Citadel called Guided Research just for these types.

Classes for this archetype: Rogue, Druid, Wizard, some Clerics and Warlocks. 

The Guided Research House Rule

 Allow a character to make an Arcana, History, Nature, or Religion check where appropriate for the express purpose of lowering the DC on a looming Investigation check.

Take their final result and divide by 5. Lower the DC of their next Investigation check by the result. 

The Detective/Bounty Hunter

Whether law enforcement or vigilante, this character type specializes in finding and bringing a perpetrator to their employer, whether a private one or a governmental body. 

A detective/bounty hunter will most likely use Investigation when they have gathered evidence and have it lying before them, such as in a cordoned-off crime scene or in a dossier or even when they are sitting down with a drink to rest and meditate on the day’s events while trying to piece together a mystery.

Detective/Bounty Hunters will often use skills such as Perception, Survival, and Insight to track down their quarry, and while these are important, the Investigation skill will help them to find clues that others miss.

See below for more on how to know when Investigation is more appropriate than the Wisdom-based skills of Perception, Insight, and Survival.

Classes for this archetype: Rogue, Ranger, Monk, some Paladins and Fighters. 

The Villain

While typically not a player character, every great villain has a plan that strikes at the weaknesses of the PCs or whomever they are targeting. 

Allow the villain to take Investigation checks depending on their resources (spies, informants, surveillance, or previous encounters with the PCs) to make their plans more nefarious and specifically designed to give the PCs a hard time. 

Does the party have a monk? Prepare a magical slow trap. Does the party have a wizard? Hire a thief to steal their spellbook. Does the PC have a damage resistance or vulnerability? Use it or avoid it, as necessary.

In a particularly devious move here at one of the Citadel’s game tables, the villain used Investigation to discover one of the PCs was a warlock of Asmodeus.

The DM rolled a series of Investigation, Arcana, and Persuasion checks to turn Asmodeus’ favor against the party warlock, forcing the warlock to prove his worth to his patron with a series of secondary objectives and making his magic unreliable for a time.

Investigation vs. Perception 

Many times, when the DM calls for an Investigation check, the PCs ask for Perception instead. Often the DM will let it slide, and the PCs can choose.

However, there is one sure way to know if Investigation is more applicable than Perception: 

How much time is the character devoting to the search?

Perception works on what characters notice with a glance. Investigation is a targeted search. 

Let’s say, for example, you’ve lost your keys. Do you just stand in the middle of the room and look for anything that catches your eye? Or maybe you kick the table and listen for a jingle? That is a Perception check.

If you are quickly NOTICING, then you are perceiving.  

Do you open the drawers, lift the couch cushions, check through the pockets of the pants or jacket you wore yesterday (because you have changed pants, right?)? This thorough search is an Investigation. 

So if you clear a room and start checking things out in detail, make an Investigation.

If you just fidget with things and look around, make a Perception. Both can be valid, provided what you need is in line of sight. 

In terms of research, the wizard will make an Investigate check and begin pulling down specific books and pages to answer a question they have.

Meanwhile, the rogue who is just wandering around notices exactly the book that is needed — it just happens to be misshelved.

This is an example of when a player rolls a Perception check higher than another player rolls an Investigation. 

Using Investigation in Combat

Mechanically speaking, there are not many abilities that allow you to use Investigation to a numerical advantage when everybody in the room starts trying to put the pokey bits in the squishy bits. 

But… if you’re smart, you can start looking for tactical advantages.

Try sacrificing a round of combat to make an Investigation check and ask your DM for a detailed description of the room.

Is there a paperweight on the table? Now you have a use for that catapult spell. Is the bookshelf a bit wobbly? Unseen Servant!

Exactly what does that bottle of alcohol behind the bar say its proof is? A little prestidigitation and a Quickened mage hand will give you a surprise molotov cocktail.

And, of course, every smart character’s favorite question: how many exits are there in this room?

Final Thoughts

Investigation is an essential part of any game. There are mysteries to solve and reasons why you are in the sewers or wilderness commiting monter murder.

A little research can answer the kind of questions that change everything – especially if you have reason to believe whoever is bankrolling the adventure you’re on is a bit untrustworthy. 

But that never happens… right?