Ok, I get it: nobody likes to be surprised. It sucks if your passive perception is low, and the badies are always jumping out of the bushes and all getting a free round of attacks on you because one of them was super stealthy. That’s one of the big reasons everyone takes Precpetion: it alerts you to danger.
But that’s possibly also the reason you shouldn’t take it. If there are five or six players at the table, and no one has good investigation, then at certain important points of the adventure — like exploration — you suck. We talk about the importance of exploration in our episode, Playing All Three Pillars. But basically, Investigation is all about clues:
“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.” - PHB, Investigation
In order to find an object with Investigation, the object needs to have some findable clues (DM this is your job to provide). You can use Investigation to find out the Why of something that everyone can see (Perception). For example, if you enter a room filled with broken furniture, investigation is like the CSI unit figuring out how the fight went down that broke the furniture, and what sort of creatures might have been involved. It provides insight and hints about the campaign’s story, just as Insight provides clues into a character’s motives. Investigation checks can give you clues that you can follow-up on (a chance for the DM to drop more story hooks).
Remember, you don’t need proficiency with a skill to make an attempt — but it certainly helps. Often Investigation is left to Wizards, as they have the highest Intelligence scores. But I would argue that maybe your next rogue should lean into both their Intelligence ability and their Investigation skills, and here’s why: traps and secret doors. It is often frustrating for the party (and possibly the DM) at how you can never find a way to disarm a trap or a open secret doors.
That’s right: detecting a secret door is a perception check (although investigation might give you clues that it exists, like finding worn floorboards near a bookcase). But once a secret door is detected, Investigation checks are made to figure out how to open it (perhaps the book without any dust on it gets pulled out a bit to release the catch). This isn’t table rules, this is straight up DMG, Dungeon Features:
"Opening a Secret Door. Once a secret door is detected, a successful Intelligence (Investigation) check might be required to determine how to open it if the opening mechanism isn’t obvious. Set the DC according to the difficulty guidelines in chapter 8."
The same goes for disarming traps: The DMG suggests calling for an Investigation check to figure out the mechanism for the trap before performing a Dexterity check with thieves tools to deactivate or sabotage it.
If you want to play investigation cool, think Sherlock Holmes. Think about how your character has the powers to deduce situations. Think CSI, and how your character can reconstruct a crime scene. Put investigation into your roleplay, and you will have lots of opportunities to help the DM move the story forward.
Then, just accept that you are going to get surprised in combat and place yourself somewhere in the middle of the marching order. You’ll be fine. Go #TeamInvest!
(Credit: Header image by DevBurmak, a freelance artist on Deviant Art who is open for commisions!)