How to Play an Investigator in D&D

Investigator Guide

The Investigator Class lets you hunt down vampires, werewolves, and other things that go bump in the night using your wits, a Crossbow, and a book brimming with ritual magic. You’re John Constantine, the Winchester brothers, or Hellboy. But how to manage all those features in the midst of a hunt? This guide will help you sort out your Investigator and get you ready for some paranormal investigations.

Weak Points

Perhaps surprisingly, the Investigator is almost as deadly in combat as a Rogue or Fighter. Instead of attacking several times, however, an Investigator hits their target where they’re weakest. Two features power this style of play: Finisher and Exploit Weakness.

Finisher

Finisher is very simple: when an enemy is Bloodied, you gain an extra 1d8 damage on an attack! You only gain this damage once per turn, and it scales slowly on the Investigator Features table (we’ll discuss why it’s so sluggish shortly!) 

Exploit Weakness

Starting at level 5, you gain Exploit Weakness — the Investigator’s bespoke replacement for Extra Attack. It does two things on a hit:

1. The target loses all of its Damager Resistances until the start of your next turn, including against this attack.
2. The target has Vulnerability to one damage type you deal.

This Vulnerability is your big damage feature! It doesn’t stack with multiclass features, but it does stack with Finisher, so try to make sure the target is Bloodied before you strike it. You only roll for damage once per turn, but then you double everything you roll for a huge final number. With any luck, the target won’t be alive to fight back.

Trinkets and Incantations

Every turn, you get a big choice for your Bonus Action: do you use a Trinket, a Ritual, or maybe a useful subclass feature?

Trinkets

All Investigators get a set of Trinkets in their subclass, and you also get a set of Holy Trinkets at level 7. All of your Trinkets, including Holy Trinkets, share the same pool of uses, which is listed on the Investigator features table. 

Importantly, most Trinkets are Bonus Actions and give you unique capabilities in and out of combat. A Detective, for example, can cast Misty Step, Invisibility, or Knock as a Bonus Action.

Rushed Incantation

The Investigator spell list contains a smattering of useful combat spells that you can cast as a Ritual. This would be all but useless in combat (how often do you have time to Ritual-cast a small buff like Heroism just before a fight?) without Rushed Incantation. Each use of Rushed Incantation lets you cast a spell of any level from your Grimoire as a Bonus Action! Once again, you have limited uses, but many more than you might at first anticipate.

Your Ritual spells are often how you’ll keep yourself alive in combat. And because they’re always a Bonus Action, you should be able to keep up damage every turn without taking downtime to protect yourself with a quick spell!

Your Grimoire

Investigators carry a book of Rituals called a Grimoire. In fact, many spells that aren’t normally Rituals count as Rituals for you! You’ll want to carry a mix of critical survival and exploration spells, along with a smattering of whatever you think will serve you well in an adventure. Just like a Wizard, you can pick up additional Ritual spells to add to your list over the course of a campaign, so you should have abundant options by later levels! 

As an Investigator, you should be able to solve tons of utility and investigation-focused problems with ease. Need to track someone? Cast Clue! Need to infiltrate a building? Cast Disguise Self or Spider Climb or Knock! Imagine yourself as a walking utility belt, with each Ritual solving one or two problems you might encounter in the adventuring day. 

Additionally, these two spells are almost critical to the class’s defenses, so you’re best served by adding them to your Grimoire at the first opportunity:

Transient Bulwark. This spell is extremely useful for your survival! Once you cast it, the next attack targeting you has an automatic -10 to its roll — it’s almost guaranteed to miss! Of course, you’ll need to cast it frequently to keep the buff up throughout a fight.

After Image. This spell is effectively Mirror Image, with a couple of key differences: you have only one illusory duplicate, and it comes back whenever you move 15 feet or more or take the Dodge action. Much like Transient Bulwark, this spell can reliably help you avoid attacks in combat that would otherwise take you out. With some mobility (always a smart approach for less-tanky classes) you can easily regenerate your double and avoid another attack.

Roleplaying an Investigator

Whenever things go bump in the night, you bump back. It’s hard work for only the skilled and determined, and every Investigator has a peculiar combination of resourcefulness and luck. As you prepare to play an Investigator at your table, consider how they came into this line of work, how their background help keeps them one step ahead of the horrors, and how such a person expresses themselves.

Here are some personality traits, bonds, ideals, and flaws hand-picked for the Investigator class. Start by choosing a personality trait from the following list, or rolling a d8 to choose one at random.

Investigator Personality Traits

1. I treat everyday conversation like an interrogation. What aren’t they telling me?
2. I cannot stand animals of any sort, especially those which remind me of vampires, werewolves, or magical familiars.
3. I never blink. Seriously, it’s probably a medical condition.
4. Whenever I get a free moment, I add notes to my enormous conspiracy board.
5. At any given time, I’m half-sure the person I’m talking to is a werewolf.
6. I’m such a night owl that being awake in the daytime is exhausting to even think about.
7. I fall in love at first sight with damn near every beautiful person I meet.
8. When I’m absolutely, positively sure I’m alone, I monologue to myself.

What do you want?

These are your bonds, the things you must do whether you want to or not, and they help you make decisions about what to do in a given situation. Choose one from the following list, or roll a d6 to choose one at random.

Investigator Bonds

1. I aim to kill an infamous vampire, even if it’s the last thing I do.
2. My collection of magical trinkets is missing a few crucial, cursed additions.
3. I come from a long line of monster hunters; those who survive expect me to further the legacy to a new generation.
4. I’m cataloging every type of lycanthropy in an attempt to uncover an alchemical cure.
5. Evil seeps into the world from an unspeakable dimension, and only a forgotten ritual can stop it.
6. I’ve uncovered a massive conspiracy, and nobody else can see the full picture.

Why do you want it?

These are your ideals, the raison d’être that drives you when no specific course of action is available. Choose one from the following list, or roll a d6 to choose one at random.

Investigator Ideals

1. Deduction. Every case has an explanation, supernatural or not. (Neutral)
2. Protection. I dabble with the occult to keep others safe from it. (Good)
3. Vigilantism. Sometimes I have to break a few rules to get the facts. (Chaotic)
4. Greed. I’ll take any case, as long as it pays well enough. (Neutral)
5. Extermination. Kill all the people summoning monsters, then kill all the monsters: problem solved. (Evil)
6. Secrets. How bad can forbidden knowledge be? (Chaotic)

What gets in your way?

These are your flaws, the personal vices and saboteurs that might cause you to act against your best interests. Choose one from the following list, or roll a d6 to choose one at random.

Investigator Flaws

1. My curiosity brings me to some truly frightening corners of magical practice.
2. I don’t trust anyone, not even my own party.
3. Whenever the evidence is against my case, I would rather double down on my theory than admit I’m wrong.
4. I rely on smoke, drink, or other substances in order to keep a level head while on the job.
5. I have a positively ghoulish sense of humor.
6. Crossbow first, questions later.

More resources for playing an Investigator

If you’re ready to build your Investigator and start your crusade against monsters, you can use this custom character sheet with all your Trinkets, Incantations, and features on one sheet. If you’re a true archivist with an itch to collect, click here to find everything we’ve ever written about the Investigator.