How to Use the Assassin’s Infiltration Expertise in D&D
Most likely, the name conjures images of a dark, cloaked figure who lurks in the shadows, waiting for the opportune moment to pierce her unwary opponent’s rib cage with a poisoned dagger. The weapon may change, the gender may vary, and you might even replace the shadows of an abandoned alleyway for the bustling crowd of a popular tavern.
Still, whatever combination you envision of stealth and sneak attack, the truth is that most Dungeons & Dragons assassins lean heavily into the “grim death” elements in the archetype’s focus on the “grim art of death.”
But the assassin has far more to contribute to an adventure than their mere combat prowess. In fact, one could even argue that an assassin who focuses too keenly on dealing death will end up missing all of the “artistic” potential in the archetype’s Infiltration Expertise.
An Ability for Moving Stories Forward
The Infiltration Expertise ability reads like the heart of a spy novel:
“Starting at 9th level, you can unfailingly create false identities for yourself. You must spend seven days and 25 gp to establish the history, profession, and affiliations for an identity […] Thereafter, if you adopt the new identity as a disguise, other creatures believe you to be that person until given an obvious reason not to.”
Notably, the assassin gains this ability at 9th level, which is just before the Dungeon Master’s Guide suggests that the player characters are graduating from their stint as “Heroes of the Realm” to become “Masters of the Realm.” In other words, the assassin who can infiltrate businesses, governments, secret societies and military outposts at will is right at home in a campaign shifting from stories focused on adventurers who have “found their place in the world and have begun to involve themselves in the dangers that surround them” to stories in which the characters “broker peace between nations or lead them into war.”
Lacking access to high-level spells, the assassin can nonetheless use their Infiltration Expertise to play a significant role in your campaign behind-the-scenes and outside of combat.
The ability doesn’t allow your assassin to take the place of another character, so they can’t assassinate the king or queen and take his or her place. But if you’re clever, you can still use the ability in all sorts of manipulative and insidious ways—even ways devoted to the cause of good.
Deception Is Your Friend
This means you want to give them proficiency in the skill and then double their proficiency bonus with the rogue’s Expertise ability. You will also likely want to give your character a high Charisma score to capitalize upon your proficiency in Deception, and you might even give them feats such as Lucky, which can be used to ensure their Deception succeeds at critical moments—such as when the king’s guards and mage ask your character why no one had been informed that your rogue was going to inspect the royal armory…
As Deception becomes second nature to your assassin, you will—as a player—want to dream up all manner of cover stories and ways to utilize them. This imaginative work can prove compelling both in and out of the game. Does your party need someone to get inside the wizard’s fortress to unlock the gate? Maybe you can get yourself inside with the hired help—or the delivery from the local bakery. It can’t be too hard to establish yourself with the bakery, but you might need another lie behind that identity, and another behind that, and behind that. Each thread in the web of lies can be either a matter of rote—or a whole story all of its own.
You have clothes to purchase or steal. Sealed letters to forge. Goods to buy and sell. You may spend so much time trading and moving goods that your assassin might very well double as a merchant.
Indeed, your rogue will have all the skills for the work. In addition to the sort of Deception that would allow them to pass well water as blessed holy water or potions of Mage Armor, they may very well want to invest heavily in Insight, Perception, and Sleight of Hand. When your assassin is working their way through the ranks of the Thieves’ Guild to learn who’s really at the head of it, they’ll likely find themselves searched and questioned multiple times—and they’ll need to be better at concealing and uncovering truths than the skilled individuals standing around them.
Working with a Team
Ultimately, the most formidable challenge to your assassin’s Infiltration Expertise is likely one that has nothing to do with their adversaries—but with your friends.
The thing is that Dungeons & Dragons is a team game. A group game. One you typically play with your friends (and sometimes with your coworkers). Together.
The assassin’s role has always been a bit solitary. Whether they’re slinking through the shadows toward their mark or using their Infiltration Expertise to orchestrate the downfall of a local government, they’re naturally inclined toward going places and using skills that don’t really want their adventuring buddies tagging along.
This, then, is where it’s most important to think creatively about your assassin’s Infiltration Expertise. It is, after all, a skill for behind-the-scenes exploits, and the easiest way to resolve those exploits might be to work them out with your Quest Master between sessions and apart from the rest of your party.
Even when that’s not a possibility, you can still think of the Infiltration Expertise ability as something you do “unfailingly” to help your group. All you need is a week, and you can—without fail—pass yourself off as someone who might help your party meet the right people, get into the right places, and uncover the truths people would have taken to their graves if you had just run into them in the streets or on the battlefield and blasted them with Fireballs and perforated them with arrows.
In this case, it might help to think of your Infiltration Expertise as a ritual that takes one week to cast and that you can cast over and over. The fact that the Player’s Handbook explicitly states you “unfailingly create false identities” with this ability is reason enough for your friends to consider giving you the week whenever circumstances allow it. Indeed, you might even begin each adventure by telling the Quest Master which identities you’ve created. Few other characters have such creative ways to use their downtime, and you can get ahead of your adventures by establishing useful identities in all the various cities you expect to visit, each of which should ideally suggest a measure of access typically denied to other people:
Ambassador from a neighboring kingdom
Merchant of rare goods
Instructor of music, acting, fencing, or whatever else might suit the local nobles
When you really take the time to think about it, the assassin’s Infiltration Expertise is tremendously flexible and powerful. It needs to be—as it’s the counterpart to the Arcane Trickster’s spell-casting—and it might help to think of the ability the way that sorcerers think of their spells: it will work, somehow.
The fun is in dreaming up the ways that it will work. Lying, cheating, stealing, and impersonating others will never be so much fun as when you’re a 5th edition assassin. Try it for yourself!